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A003415 a(n) = n' = arithmetic derivative of n: a(0) = a(1) = 0, a(prime) = 1, a(mn) = m*a(n) + n*a(m).
(Formerly M3196)

%I M3196

%S 0,0,1,1,4,1,5,1,12,6,7,1,16,1,9,8,32,1,21,1,24,10,13,1,44,10,15,27,

%T 32,1,31,1,80,14,19,12,60,1,21,16,68,1,41,1,48,39,25,1,112,14,45,20,

%U 56,1,81,16,92,22,31,1,92,1,33,51,192,18,61,1,72,26,59,1,156,1,39,55,80,18,71

%N a(n) = n' = arithmetic derivative of n: a(0) = a(1) = 0, a(prime) = 1, a(mn) = m*a(n) + n*a(m).

%C Can be extended to negative numbers by defining a(-n) = -a(n).

%C Based on the product rule for differentiation of functions: for functions f(x) and g(x), (fg)' = f'g + fg'. So with numbers, (ab)' = a'b + ab'. This implies 1' = 0. - _Kerry Mitchell_, Mar 18 2004

%C The derivative of a number x with respect to a prime number p as being the number "dx/dp" = (x-x^p)/p, which is an integer due to Fermat's little theorem. - Alexandru Buium, Mar 18 2004

%C The relation (ab)' = a'b + ab' implies 1' = 0, but it does not imply p' = 1 for p a prime. In fact, any function f defined on the primes can be extended uniquely to a function on the integers satisfying this relation: f(Product_i p_i^e_i) = (Product_i p_i^e_i) * (Sum_i e_i*f(p_i)/p_i). - _Franklin T. Adams-Watters_, Nov 07 2006

%C a(m*p^p) = (m + a(m))*p^p, p prime: a(m*A051674(k))=A129283(m)*A051674(k). - _Reinhard Zumkeller_, Apr 07 2007

%C See A131116 and A131117 for record values and where they occur. - _Reinhard Zumkeller_, Jun 17 2007

%C Let n be the product of a multiset P of k primes. Consider the k-dimensional box whose edges are the elements of P. Then the (k-1)-dimensional surface of this box is 2a(n). For example, For example, 2a(25) = 20, the perimeter of a 5 X 5 square. Similarly, 2a(18) = 42, the surface area of a 2 X 3 X 3 box. - _David W. Wilson_, Mar 11 2011

%C The arithmetic derivative n' was introduced, probably for the first time, by the Spanish mathematician José Mingot Shelly in June 1911 with "Una cuestión de la teoría de los números", work presented at the "Tercer Congreso Nacional para el Progreso de las Ciencias, Granada", cf. link to the abstract on Zentralblatt MATH, and L. E. Dickson, History of the Theory of Numbers. - _Giorgio Balzarotti_, Oct 19 2013

%C a(A235991(n)) odd; a(A235992(n)) even. - _Reinhard Zumkeller_, Mar 11 2014

%C Sequence A157037 lists numbers with prime arithmetic derivative, i.e., indices of primes in this sequence. - _M. F. Hasler_, Apr 07 2015

%C Maybe the simplest "natural extension" of the arithmetic derivative, in the spirit of the above remark by _Franklin T. Adams-Watters_ (2006), is the "pi based" version where f(p) = primepi(p), see sequence A258851. When f is chosen to be the identity map (on primes), one gets A066959. - _M. F. Hasler_, Jul 13 2015

%C When n is composite, it appears that a(n) has lower bound 2*sqrt(n), with equality when n is the square of a prime, and a(n) has upper bound (n/2)*((log n)/(log 2)), with equality when n is a power of 2. - _Daniel Forgues_, Jun 22 2016

%D G. Balzarotti, P. P. Lava, La derivata aritmetica, Editore U. Hoepli, Milano, 2013

%D E. J. Barbeau, Problem, Canad. Math. Congress Notes, 5 (No. 8, April 1973), 6-7.

%D L. E. Dickson, History of the Theory of Numbers, Vol. 1, Chapter XIX, p. 451, Dover Edition, 2005. (Work originally published in 1919.)

%D A. M. Gleason et al., The William Lowell Putnam Mathematical Competition: Problems and Solutions 1938-1964, Math. Assoc. America, 1980, p. 295.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A003415/b003415.txt">Table of n, a(n) for n = 0..10000</a>

%H Krassimir T. Atanassov, <a href="http://doi.baspress.com/pdf-journal/Comptes%20Rendus_4_2013/4_2013_4.pdf">A formula for the n-th prime number</a>, Comptes rendus de l'Académie bulgare des Sciences, Tome 66, No 4, 2013.

%H E. J. Barbeau, <a href="http://dx.doi.org/10.4153/CMB-1961-013-0">Remark on an arithmetic derivative</a>, Canad. Math. Bull. vol. 4, no. 2, May 1961.

%H A. Buium, <a href="http://www.math.unm.edu/~buium">Home Page</a>

%H A. Buium, <a href="http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=GDZPPN002113260&amp;IDDOC=181984">Differential characters of Abelian varieties over p-adic fields</a>, Invent. Math. 122 (1995), no. 2, 309-340.

%H A. Buium, <a href="http://dx.doi.org/10.1215/S0012-7094-96-08216-2">Geometry of p-jets</a>, Duke Math. J. 82 (1996), no. 2, 349-367.

%H A. Buium, <a href="http://dx.doi.org/10.1006/jabr.1997.7177">Arithmetic analogues of derivations</a>, J. Algebra 198 (1997), no. 1, 290-299.

%H A. Buium, <a href="http://dx.doi.org/10.1515/crll.2000.024">Differential modular forms</a>, J. Reine Angew. Math. 520 (2000), 95-167.

%H José María Grau and Antonio M. Oller-Marcén, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL15/Oller/oller5.html">Giuga Numbers and the Arithmetic Derivative</a>, Journal of Integer Sequences, Vol. 15 (2012), #12.4.1.

%H R. K. Guy, <a href="/A003271/a003271.pdf">Letter to N. J. A. Sloane, Apr 1975</a>

%H P. Haukkanen, M. Mattila, J. K. Merikoski and T. Tossavainen, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL16/Tossavainen/tossavainen4.html">Can the Arithmetic Derivative be Defined on a Non-Unique Factorization Domain?</a>, Journal of Integer Sequences, 16 (2013), #13.1.2. - From _N. J. A. Sloane_, Feb 03 2013

%H J. Kovič, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL15/Kovic/kovic4.html">The Arithmetic Derivative and Antiderivative</a>, Journal of Integer Sequences 15 (2012), Article 12.3.8

%H Ivars Peterson, <a href="http://www.sciencenews.org/articles/20040320/mathtrek.asp">Deriving the Structure of Numbers</a>, Science News, March 20, 2004.

%H D. J. M. Shelly, <a href="http://zbmath.org/?q=an:42.0209.02">Una cuestión de la teoria de los numeros</a>, Asociation Esp. Granada 1911, 1-12 S (1911). (Abstract of ref. JFM42.0209.02 on zbMATH.org)

%H Victor Ufnarovski and Bo Åhlander, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL6/Ufnarovski/ufnarovski.html">How to Differentiate a Number</a>, J. Integer Seqs., Vol. 6, 2003, #03.3.4.

%H Linda Westrick, <a href="http://www.plouffe.fr/simon/OEIS/archive_in_pdf/intmain.pdf">Investigations of the Number Derivative</a>, Siemens Foundation competition 2003 and Intel Science Talent Search 2004.

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Arithmetic_derivative">Arithmetic derivative</a>

%F If n = Product p_i^e_i, a(n) = n * Sum (e_i/p_i).

%F For n > 1: a(n) = a(A032742(n)) * A020639(n) + A032742(n). - _Reinhard Zumkeller_, May 09 2011

%F a(n) = n * Sum_{p|n} v_p(n)/p, where v_p(n) is the largest power of the prime p dividing n. - _Wesley Ivan Hurt_, Jul 12 2015

%F For n>=2, Sum_{k=2..n}[1/a(k)] = pi(n) = A000720(n), where [x] stands for the integer part of x (see K. T. Atanassov article). - _Ivan N. Ianakiev_, Mar 22 2019

%e 6' = (2*3)' = 2'*3 + 2*3' = 1*3 + 2*1 = 5.

%e Note that for example, 2' + 3' = 1 + 1 = 2, (2+3)' = 5' = 1. So ' is not linear.

%e G.f. = x^2 + x^3 + 4*x^4 + x^5 + 5*x^6 + x^7 + 12*x^8 + 6*x^9 + 7*x^10 + ...

%p A003415 := proc(n) local B,m,i,t1,t2,t3; B := 1000000000039; if n<=1 then RETURN(0); fi; if isprime(n) then RETURN(1); fi; t1 := ifactor(B*n); m := nops(t1); t2 := 0; for i from 1 to m do t3 := op(i,t1); if nops(t3) = 1 then t2 := t2+1/op(t3); else t2 := t2+op(2,t3)/op(op(1,t3)); fi od: t2 := t2-1/B; n*t2; end;

%p A003415 := proc(n)

%p local a,f;

%p a := 0 ;

%p for f in ifactors(n)[2] do

%p a := a+ op(2,f)/op(1,f);

%p end do;

%p n*a ;

%p end proc: # _R. J. Mathar_, Apr 05 2012

%t a[ n_] := If[ Abs @ n < 2, 0, n Total[ #2 / #1 & @@@ FactorInteger[ Abs @ n]]]; (* _Michael Somos_, Apr 12 2011 *)

%t dn[0] = 0; dn[1] = 0; dn[n_?Negative] := -dn[-n]; dn[n_] := Module[{f = Transpose[FactorInteger[n]]}, If[PrimeQ[n], 1, Total[n*f[[2]]/f[[1]]]]]; Table[dn[n], {n, 0, 100}] (* _T. D. Noe_, Sep 28 2012 *)

%o (PARI) A003415(n) = {local(fac);if(n<1,0,fac=factor(n);sum(i=1,matsize(fac)[1],n*fac[i,2]/fac[i,1]))} /* _Michael B. Porter_, Nov 25 2009 */

%o (PARI) A003415(n,f)=sum(i=1,#f=factor(n)~,n/f[1,i]*f[2,i]) \\ _M. F. Hasler_, Sep 25 2013

%o (Haskell)

%o a003415 0 = 0

%o a003415 n = ad n a000040_list where

%o ad 1 _ = 0

%o ad n ps'@(p:ps)

%o | n < p * p = 1

%o | r > 0 = ad n ps

%o | otherwise = n' + p * ad n' ps' where

%o (n',r) = divMod n p

%o -- _Reinhard Zumkeller_, May 09 2011

%o (MAGMA) Ad:=func<h | h*(&+[Factorisation(h)[i][2]/Factorisation(h)[i][1]: i in [1..#Factorisation(h)]])>; [n le 1 select 0 else Ad(n): n in [0..80]]; // _Bruno Berselli_, Oct 22 2013

%o (Python)

%o from sympy import factorint

%o def A003415(n):

%o ....return sum([int(n*e/p) for p,e in factorint(n).items()]) if n > 1 else 0

%o # _Chai Wah Wu_, Aug 21 2014

%o (Sage)

%o def A003415(n):

%o a = 0; F = []

%o if n > 0: F = list(factor(n))

%o return n*sum(f[1]/f[0] for f in F)

%o [A003415(n) for n in range(79)] # _Peter Luschny_, Aug 23 2014

%o (GAP)

%o A003415:= Concatenation([0,0],List(List([2..10^3],Factors),

%o i->Product(i)*Sum(i,j->1/j))); # _Muniru A Asiru_, Aug 31 2017

%Y Cf. A086134 (least prime factor of n').

%Y Cf. A086131 (greatest prime factor of n').

%Y Cf. A068719 (derivative of 2n).

%Y Cf. A068720 (derivative of n^2).

%Y Cf. A068721 (derivative of n^3).

%Y Cf. A001787 (derivative of 2^n).

%Y Cf. A027471 (derivative of 3^n).

%Y Cf. A085708 (derivative of 10^n).

%Y Cf. A068327 (derivative of n^n).

%Y Cf. A024451 (derivative of p#).

%Y Cf. A068237 (numerator of derivative of 1/n).

%Y Cf. A068238 (denominator of derivative of 1/n).

%Y Cf. A068328 (derivative of squarefree numbers).

%Y Cf. A068311 (derivative of n!).

%Y Cf. A168386 (derivative of n!!).

%Y Cf. A260619 (derivative of hyperfactorial(n)).

%Y Cf. A260620 (derivative of superfactorial(n)).

%Y Cf. A068312 (derivative of triangular numbers).

%Y Cf. A068329 (derivative of Fibonacci(n)).

%Y Cf. A096371 (derivative of partition number).

%Y Cf. A099301 (derivative of d(n)).

%Y Cf. A099310 (derivative of phi(n)).

%Y Cf. A327860 (derivative of prime product form of primorial base expansion of n).

%Y Cf. A068346 (second derivative of n).

%Y Cf. A099306 (third derivative of n).

%Y Cf. A258644 (fourth derivative of n).

%Y Cf. A258645 (fifth derivative of n).

%Y Cf. A258646 (sixth derivative of n).

%Y Cf. A258647 (seventh derivative of n).

%Y Cf. A258648 (eighth derivative of n).

%Y Cf. A258649 (ninth derivative of n).

%Y Cf. A258650 (tenth derivative of n).

%Y Cf. A185232 (n-th derivative of n).

%Y Cf. A258651 (A(n,k) = k-th arithmetic derivative of n).

%Y Cf. A085731 (gcd(n,n')).

%Y Cf. A098699 (least x such that x' = n, antiderivative of n).

%Y Cf. A098700 (n such that x' = n has no integer solution).

%Y Cf. A099302 (number of solutions to x' = n).

%Y Cf. A099303 (greatest x such that x' = n).

%Y Cf. A051674 (n such that n' = n).

%Y Cf. A083347 (n such that n' < n).

%Y Cf. A083348 (n such that n' > n).

%Y Cf. A099304 (least k such that (n+k)' = n' + k').

%Y Cf. A099305 (number of solutions to (n+k)' = n' + k').

%Y Cf. A328235 (least k > 0 such that (n+k)' = u * n' for some natural number u).

%Y Cf. A328236 (least m > 1 such that (m*n)' = u * n' for some natural number u).

%Y Cf. A099307 (least k such that the k-th arithmetic derivative of n is zero).

%Y Cf. A099308 (k-th arithmetic derivative of n is zero for some k).

%Y Cf. A099309 (k-th arithmetic derivative of n is nonzero for all k).

%Y Cf. A129150 (n-th derivative of 2^3).

%Y Cf. A129151 (n-th derivative of 3^4).

%Y Cf. A129152 (n-th derivative of 5^6).

%Y Cf. A189481 (x' = n has a unique solution).

%Y Cf. A190121 (partial sums).

%Y Cf. A258057 (first differences).

%Y Cf. A229501 (n divides the n-th partial sum).

%Y Cf. A165560 (parity).

%Y Cf. A235991 (n' is odd), A235992 (n' is even).

%Y Cf. A327863, A327864, A327865 (n' is a multiple of 3, 4, 5).

%Y Cf. A157037 (n' is prime), A192192 (n'' is prime), A328239 (n''' is prime).

%Y Cf. A328393 (n' is squarefree), A328234 (squarefree and > 1).

%Y Cf. A328244 (n'' is squarefree), A328246 (n''' is squarefree).

%Y Cf. A328303 (n' is not squarefree), A328252 (n' is squarefree, but n is not).

%Y Cf. A328248 (least k such that the (k-1)-th derivative of n is squarefree).

%Y Cf. A328251 (k-th arithmetic derivative is never squarefree for any k >= 0).

%Y Cf. A256750 (least k such that the k-th derivative is either 0 or has a factor p^p).

%Y Cf. A327928 (number of distinct primes p such that p^p divides n').

%Y Cf. A327929 (n' has at least one divisor of the form p^p).

%Y Cf. A327978 (n' is primorial number > 1).

%Y Cf. A328243 (n' is a partial sum of primorial numbers and larger than one).

%Y Cf. A328310 (maximal prime exponent of n' minus maximal prime exponent of n).

%Y Cf. A328320 (max. prime exponent of n' is less than that of n).

%Y Cf. A328321 (max. prime exponent of n' is >= that of n).

%Y Cf. A328383 (least k such that the k-th derivative of n is either a multiple or a divisor of n, but not both).

%Y Cf. A263111 (the ordinal transform of a).

%Y Cf. A300251, A319684 (Möbius and inverse Möbius transform).

%Y Cf. A305809 (Dirichlet convolution square).

%Y Cf. A069359 (similar formula which agrees on squarefree numbers).

%Y Cf. A258851 (the pi-based arithmetic derivative of n).

%Y Cf. A328768, A328769 (primorial-based arithmetic derivatives of n).

%Y Cf. A328845, A328846 (Fibonacci-based arithmetic derivatives of n).

%Y Cf. A302055, A327963, A327965, A328099 (for other variants and modifications).

%Y Cf. A038554 (another sequence using "derivative" in its name, but involving binary expansion of n).

%K nonn,easy,nice,hear,look

%O 0,5

%A _N. J. A. Sloane_, _R. K. Guy_

%E More terms from _Michel ten Voorde_, Apr 11 2001

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Last modified November 21 00:08 EST 2019. Contains 329348 sequences. (Running on oeis4.)