

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)


444



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

0,5


COMMENTS

Can be extended to negative numbers by defining a(n) = a(n).
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
The derivative of a number x with respect to a prime number p as being the number "dx/dp" = (xx^p)/p, which is an integer due to Fermat's little theorem.  Alexandru Buium, Mar 18 2004
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. AdamsWatters, Nov 07 2006
a(m*p^p) = (m + a(m))*p^p, p prime: a(m*A051674(k))=A129283(m)*A051674(k).  Reinhard Zumkeller, Apr 07 2007
See A131116 and A131117 for record values and where they occur.  Reinhard Zumkeller, Jun 17 2007
Let n be the product of a multiset P of k primes. Consider the kdimensional box whose edges are the elements of P. Then the (k1)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
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
a(A235991(n)) odd; a(A235992(n)) even.  Reinhard Zumkeller, Mar 11 2014
Sequence A157037 lists numbers with prime arithmetic derivative, i.e., indices of primes in this sequence.  M. F. Hasler, Apr 07 2015
Maybe the simplest "natural extension" of the arithmetic derivative, in the spirit of the above remark by Franklin T. AdamsWatters (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
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


REFERENCES

G. Balzarotti, P. P. Lava, La derivata aritmetica, Editore U. Hoepli, Milano, 2013
E. J. Barbeau, Problem, Canad. Math. Congress Notes, 5 (No. 8, April 1973), 67.
L. E. Dickson, History of the Theory of Numbers, Vol. 1, Chapter XIX, p. 451, Dover Edition, 2005. (Work originally published in 1919.)
A. M. Gleason et al., The William Lowell Putnam Mathematical Competition: Problems and Solutions 19381964, Math. Assoc. America, 1980, p. 295.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000
Krassimir T. Atanassov, A formula for the nth prime number, Comptes rendus de l'Académie bulgare des Sciences, Tome 66, No 4, 2013.
E. J. Barbeau, Remark on an arithmetic derivative, Canad. Math. Bull. vol. 4, no. 2, May 1961.
A. Buium, Home Page
A. Buium, Differential characters of Abelian varieties over padic fields, Invent. Math. 122 (1995), no. 2, 309340.
A. Buium, Geometry of pjets, Duke Math. J. 82 (1996), no. 2, 349367.
A. Buium, Arithmetic analogues of derivations, J. Algebra 198 (1997), no. 1, 290299.
A. Buium, Differential modular forms, J. Reine Angew. Math. 520 (2000), 95167.
José María Grau and Antonio M. OllerMarcén, Giuga Numbers and the Arithmetic Derivative, Journal of Integer Sequences, Vol. 15 (2012), #12.4.1.
R. K. Guy, Letter to N. J. A. Sloane, Apr 1975
P. Haukkanen, M. Mattila, J. K. Merikoski and T. Tossavainen, Can the Arithmetic Derivative be Defined on a NonUnique Factorization Domain?, Journal of Integer Sequences, 16 (2013), #13.1.2.  From N. J. A. Sloane, Feb 03 2013
J. Kovič, The Arithmetic Derivative and Antiderivative, Journal of Integer Sequences 15 (2012), Article 12.3.8.
Ivars Peterson, Deriving the Structure of Numbers, Science News, March 20, 2004.
D. J. M. Shelly, Una cuestión de la teoria de los numeros, Asociation Esp. Granada 1911, 112 S (1911). (Abstract of ref. JFM42.0209.02 on zbMATH.org)
Victor Ufnarovski and Bo Åhlander, How to Differentiate a Number, J. Integer Seqs., Vol. 6, 2003, #03.3.4.
Linda Westrick, Investigations of the Number Derivative, Siemens Foundation competition 2003 and Intel Science Talent Search 2004.
Wikipedia, Arithmetic derivative


FORMULA

If n = Product p_i^e_i, a(n) = n * Sum (e_i/p_i).
For n > 1: a(n) = a(A032742(n)) * A020639(n) + A032742(n).  Reinhard Zumkeller, May 09 2011
a(n) = n * Sum_{pn} v_p(n)/p, where v_p(n) is the largest power of the prime p dividing n.  Wesley Ivan Hurt, Jul 12 2015
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
From A.H.M. Smeets, Jan 17 2020: (Start)
Lim_{n > inf} (1/n^2)*Sum_{i=1..n} a(i) = A136141/2.
Lim_{n > inf} (1/n)*Sum_{i=1..n} a(i)/i = A136141.
a(n) = n if and only if n = p^p, where p is a prime number. (End)


EXAMPLE

6' = (2*3)' = 2'*3 + 2*3' = 1*3 + 2*1 = 5.
Note that for example, 2' + 3' = 1 + 1 = 2, (2+3)' = 5' = 1. So ' is not linear.
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 + ...


MAPLE

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 := t21/B; n*t2; end;
A003415 := proc(n)
local a, f;
a := 0 ;
for f in ifactors(n)[2] do
a := a+ op(2, f)/op(1, f);
end do;
n*a ;
end proc: # R. J. Mathar, Apr 05 2012


MATHEMATICA

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


PROG

(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 */
(PARI) apply( A003415(n)=vecsum([n/f[1]*f[2]f<factor(n+!n)~]), [0..99]) \\ M. F. Hasler, Sep 25 2013, updated Nov 27 2019
(Haskell)
a003415 0 = 0
a003415 n = ad n a000040_list where
ad 1 _ = 0
ad n ps'@(p:ps)
 n < p * p = 1
 r > 0 = ad n ps
 otherwise = n' + p * ad n' ps' where
(n', r) = divMod n p
 Reinhard Zumkeller, May 09 2011
(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
(Python)
from sympy import factorint
def A003415(n):
return sum([int(n*e/p) for p, e in factorint(n).items()]) if n > 1 else 0
# Chai Wah Wu, Aug 21 2014
(Sage)
def A003415(n):
F = [] if n == 0 else factor(n)
return n * sum(g / f for f, g in F)
[A003415(n) for n in range(79)] # Peter Luschny, Aug 23 2014
(GAP)
A003415:= Concatenation([0, 0], List(List([2..10^3], Factors),
i>Product(i)*Sum(i, j>1/j))); # Muniru A Asiru, Aug 31 2017


CROSSREFS

Cf. A086134 (least prime factor of n').
Cf. A086131 (greatest prime factor of n').
Cf. A068719 (derivative of 2n).
Cf. A068720 (derivative of n^2).
Cf. A068721 (derivative of n^3).
Cf. A001787 (derivative of 2^n).
Cf. A027471 (derivative of 3^n).
Cf. A085708 (derivative of 10^n).
Cf. A068327 (derivative of n^n).
Cf. A024451 (derivative of p#).
Cf. A068237 (numerator of derivative of 1/n).
Cf. A068238 (denominator of derivative of 1/n).
Cf. A068328 (derivative of squarefree numbers).
Cf. A068311 (derivative of n!).
Cf. A168386 (derivative of n!!).
Cf. A260619 (derivative of hyperfactorial(n)).
Cf. A260620 (derivative of superfactorial(n)).
Cf. A068312 (derivative of triangular numbers).
Cf. A068329 (derivative of Fibonacci(n)).
Cf. A096371 (derivative of partition number).
Cf. A099301 (derivative of d(n)).
Cf. A099310 (derivative of phi(n)).
Cf. A327860 (derivative of prime product form of primorial base expansion of n).
Cf. A068346 (second derivative of n).
Cf. A099306 (third derivative of n).
Cf. A258644 (fourth derivative of n).
Cf. A258645 (fifth derivative of n).
Cf. A258646 (sixth derivative of n).
Cf. A258647 (seventh derivative of n).
Cf. A258648 (eighth derivative of n).
Cf. A258649 (ninth derivative of n).
Cf. A258650 (tenth derivative of n).
Cf. A185232 (nth derivative of n).
Cf. A258651 (A(n,k) = kth arithmetic derivative of n).
Cf. A085731 (gcd(n,n')).
Cf. A098699 (least x such that x' = n, antiderivative of n).
Cf. A098700 (n such that x' = n has no integer solution).
Cf. A099302 (number of solutions to x' = n).
Cf. A099303 (greatest x such that x' = n).
Cf. A051674 (n such that n' = n).
Cf. A083347 (n such that n' < n).
Cf. A083348 (n such that n' > n).
Cf. A099304 (least k such that (n+k)' = n' + k').
Cf. A099305 (number of solutions to (n+k)' = n' + k').
Cf. A328235 (least k > 0 such that (n+k)' = u * n' for some natural number u).
Cf. A328236 (least m > 1 such that (m*n)' = u * n' for some natural number u).
Cf. A099307 (least k such that the kth arithmetic derivative of n is zero).
Cf. A099308 (kth arithmetic derivative of n is zero for some k).
Cf. A099309 (kth arithmetic derivative of n is nonzero for all k).
Cf. A129150 (nth derivative of 2^3).
Cf. A129151 (nth derivative of 3^4).
Cf. A129152 (nth derivative of 5^6).
Cf. A189481 (x' = n has a unique solution).
Cf. A190121 (partial sums).
Cf. A258057 (first differences).
Cf. A229501 (n divides the nth partial sum).
Cf. A165560 (parity).
Cf. A235991 (n' is odd), A235992 (n' is even).
Cf. A327863, A327864, A327865 (n' is a multiple of 3, 4, 5).
Cf. A157037 (n' is prime), A192192 (n'' is prime), A328239 (n''' is prime).
Cf. A328393 (n' is squarefree), A328234 (squarefree and > 1).
Cf. A328244 (n'' is squarefree), A328246 (n''' is squarefree).
Cf. A328303 (n' is not squarefree), A328252 (n' is squarefree, but n is not).
Cf. A328248 (least k such that the (k1)th derivative of n is squarefree).
Cf. A328251 (kth arithmetic derivative is never squarefree for any k >= 0).
Cf. A256750 (least k such that the kth derivative is either 0 or has a factor p^p).
Cf. A327928 (number of distinct primes p such that p^p divides n').
Cf. A327929 (n' has at least one divisor of the form p^p).
Cf. A327978 (n' is primorial number > 1).
Cf. A328243 (n' is a partial sum of primorial numbers and larger than one).
Cf. A328310 (maximal prime exponent of n' minus maximal prime exponent of n).
Cf. A328320 (max. prime exponent of n' is less than that of n).
Cf. A328321 (max. prime exponent of n' is >= that of n).
Cf. A328383 (least k such that the kth derivative of n is either a multiple or a divisor of n, but not both).
Cf. A263111 (the ordinal transform of a).
Cf. A300251, A319684 (Möbius and inverse Möbius transform).
Cf. A305809 (Dirichlet convolution square).
Cf. A069359 (similar formula which agrees on squarefree numbers).
Cf. A258851 (the pibased arithmetic derivative of n).
Cf. A328768, A328769 (primorialbased arithmetic derivatives of n).
Cf. A328845, A328846 (Fibonaccibased arithmetic derivatives of n).
Cf. A302055, A327963, A327965, A328099 (for other variants and modifications).
Cf. A038554 (another sequence using "derivative" in its name, but involving binary expansion of n).
Sequence in context: A024919 A328385 A328099 * A302055 A086300 A028271
Adjacent sequences: A003412 A003413 A003414 * A003416 A003417 A003418


KEYWORD

nonn,easy,nice,hear,look


AUTHOR

N. J. A. Sloane, R. K. Guy


EXTENSIONS

More terms from Michel ten Voorde, Apr 11 2001


STATUS

approved



