

A001563


a(n) = n*n! = (n+1)!  n!.
(Formerly M3545 N1436)


155



0, 1, 4, 18, 96, 600, 4320, 35280, 322560, 3265920, 36288000, 439084800, 5748019200, 80951270400, 1220496076800, 19615115520000, 334764638208000, 6046686277632000, 115242726703104000, 2311256907767808000, 48658040163532800000, 1072909785605898240000
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OFFSET

0,3


COMMENTS

A similar sequence, with the initial 0 replaced by 1, namely A094258, is defined by the recurrence a(2) = 1, a(n) = a(n1)*(n1)^2/(n2).  Andrey Ryshevich (ryshevich(AT)notes.idlab.net), May 21 2002
Denominators in power series expansion of E_1(x) + gamma + log(x), x > 0.  Michael Somos, Dec 11 2002
If all the permutations of any length k are arranged in lexicographic order, the nth term in this sequence (n <= k) gives the index of the permutation that rotates the last n elements one position to the right. E.g., there are 24 permutations of 4 items. In lexicographic order they are (0,1,2,3), (0,1,3,2), (0,2,1,3), ... (3,2,0,1), (3,2,1,0). Permutation 0 is (0,1,2,3), which rotates the last 1 element, i.e., it makes no change. Permutation 1 is (0,1,3,2), which rotates the last 2 elements. Permutation 4 is (0,3,1,2), which rotates the last 3 elements. Permutation 18 is (3,0,1,2), which rotates the last 4 elements. The same numbers work for permutations of any length.  Henry H. Rich (glasss(AT)bellsouth.net), Sep 27 2003
Stirling transform of a(n+1)=[4,18,96,600,...] is A083140(n+1)=[4,22,154,...].  Michael Somos, Mar 04 2004
Stirling transform of a(n)=[1,4,18,96,...] is A069321(n)=[1,5,31,233,...].
Partial sums of a(n)=[0,1,4,18,...] is A033312(n+1)=[0,1,5,23,...].
Binomial transform of A000166(n+1)=[0,1,2,9,...] is a(n)=[0,1,4,18,...].
Binomial transform of A000255(n+1)=[1,3,11,53,...] is a(n+1)=[1,4,18,96,...].
Binomial transform of a(n)=[0,1,4,18,...] is A093964(n)=[0,1,6,33,...].
Partial sums of A001564(n)=[1,3,4,14,...] is a(n+1)=[1,4,18,96,...].
(End)
Number of small descents in all permutations of [n+1]. A small descent in a permutation (x_1,x_2,...,x_n) is a position i such that x_i  x_(i+1) =1. Example: a(2)=4 because there are 4 small descents in the permutations 123, 13\2, 2\13, 231, 312, 3\2\1 of {1,2,3} (shown by \). a(n)=Sum_{k=0..n1}k*A123513(n,k).  Emeric Deutsch, Oct 02 2006
Equivalently, in the notation of David, Kendall and Barton, p. 263, this is the total number of consecutive ascending pairs in all permutations on n+1 letters (cf. A010027).  N. J. A. Sloane, Apr 12 2014
a(n1) is the number of permutations of n in which n is not fixed; equivalently, the number of permutations of the positive integers in which n is the largest element that is not fixed.  Franklin T. AdamsWatters, Nov 29 2006
Number of factors in a determinant when writing down all multiplication permutations.  Mats Granvik, Sep 12 2008
a(n) is also the sum of the positions of the lefttoright maxima in all permutations of [n]. Example: a(3)=18 because the positions of the lefttoright maxima in the permutations 123,132,213,231,312 and 321 of [3] are 123, 12, 13, 12, 1 and 1, respectively and 1+2+3+1+2+1+3+1+2+1+1=18.  Emeric Deutsch, Sep 21 2008
Preface the series with another 1: (1, 1, 4, 18, ...); then the next term = dot product of the latter with "n occurs n times". Example: 96 = (1, 1, 4, 8) dot (4, 4, 4, 4) = (4 + 4 + 16 + 72).  Gary W. Adamson, Apr 17 2009
a(n) is also the number of minimum (n)distinguishing labelings of the star graph S_{n+1} on n+1 nodes.  Eric W. Weisstein, Oct 14 2014
When the numbers denote finite permutations (as row numbers of A055089) these are the circular shifts to the right, i.e., a(n) is the permutation with the cycle notation (0 1 ... n1 n). Compare array A051683 for circular shifts to the right in a broader sense. Compare sequence A007489 for circular shifts to the left.  Tilman Piesk, Apr 29 2017
a(n1) is the number of permutations on n elements with no cycles of length n.  Dennis P. Walsh, Oct 02 2017
The number of pandigital numbers in base n+1, such that each digit appears exactly once. For example, there are a(9) = 9*9! = 3265920 pandigital numbers in base 10 (A050278).  Amiram Eldar, Apr 13 2020


REFERENCES

A. T. Benjamin and J. J. Quinn, Proofs that really count: the art of combinatorial proof, M.A.A. 2003, id. 218.
J. M. Borwein and P. B. Borwein, Pi and the AGM, Wiley, 1987, p. 336.
F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 263.
L. B. W. Jolley, Summation of series, Dover (1961).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS



FORMULA

E.g.f.: x / (1  x)^2.
a(n) = A021009(n, 1), n >= 0. (End)
The coefficient of y^(n1) in expansion of (y+n!)^n, n >= 1, gives the sequence 1, 4, 18, 96, 600, 4320, 35280, ...  Artur Jasinski, Oct 22 2007
Integral representation as nth moment of a function on a positive halfaxis, in Maple notation: a(n) = Integral_{x=0..oo} (x^n*(x*(x1)*exp(x)) dx, for n>=0. This representation may not be unique.  Karol A. Penson, Sep 27 2001
a(0) = 0, a(n) = (n  1) * (1 + Sum_{i=1..n1} a(i)) for i > 0.  Gerald McGarvey, Jun 11 2004
Arises in the denominators of the following identities: Sum_{n>=1} 1/(n*(n+1)*(n+2)) = 1/4, Sum_{n>=1} 1/(n*(n+1)*(n+2)*(n+3)) = 1/18, Sum_{n>=1} 1/(n*(n+1)*(n+2)*(n+3)*(n+4)) = 1/96, etc. The general expression is Sum_{n>=k} 1/C(n, k) = k/(k1).  Dick Boland, Jun 06 2005 [And the general expression implies that Sum_{n>=1} 1/(n*(n+1)*...*(n+k1)) = (Sum_{n>=k} 1/C(n, k))/k! = 1/((k1)*(k1)!) = 1/a(k1), k >= 2.  Jianing Song, May 07 2023]
a(n) = Sum_{m=2..n+1} Stirling1(n+1, m), n >= 1 and a(0):=0, where Stirling1(n, m) = A048994(n, m), n >= m = 0.
The reciprocals of a(n) are the lead coefficients in the factored form of the polynomials obtained by summing the binomial coefficients with a fixed lower term up to n as the upper term, divided by the term index, for n >= 1: Sum_{k = i..n} C(k, i)/k = (1/a(n))*n*(n1)*..*(ni+1). The first few such polynomials are Sum_{k = 1..n} C(k, 1)/k = (1/1)*n, Sum_{k = 2..n} C(k, 2)/k = (1/4)*n*(n1), Sum_{k = 3..n} C(k, 3)/k = (1/18)*n*(n1)*(n2), Sum_{k = 4..n} C(k, 4)/k = (1/96)*n*(n1)*(n2)*(n3), etc.  Peter Breznay (breznayp(AT)uwgb.edu), Sep 28 2008
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..k} binomial(k,j)*Stirling1(n,k)* Stirling2(j,i)*x^(kj) then a(n) = (1)^(n1)*f(n,1,2), (n >= 1).  Milan Janjic, Mar 01 2009
Sum_{n>=1} (1)^(n+1)/a(n) = 0.796599599... [Jolley eq. 289]
G.f.: 2*x*Q(0), where Q(k) = 1  1/(k+2  x*(k+2)^2*(k+3)/(x*(k+2)*(k+3)1/Q(k+1))); (continued fraction).  Sergei N. Gladkovskii, Apr 19 2013
G.f.: W(0)*(1sqrt(x))  1, where W(k) = 1 + sqrt(x)/( 1  sqrt(x)*(k+2)/(sqrt(x)*(k+2) + 1/W(k+1) )); (continued fraction).  Sergei N. Gladkovskii, Aug 18 2013
G.f.: T(0)/x  1/x, where T(k) = 1  x^2*(k+1)^2/( x^2*(k+1)^2  (1x2*x*k)*(13*x2*x*k)/T(k+1) ); (continued fraction).  Sergei N. Gladkovskii, Oct 17 2013
G.f.: Q(0)*(1x)/x  1/x, where Q(k) = 1  x*(k+1)/( x*(k+1)  1/(1  x*(k+1)/( x*(k+1)  1/Q(k+1) ))); (continued fraction).  Sergei N. Gladkovskii, Oct 22 2013
Dfinite with recurrence: a(n) +(n2)*a(n1) +(n1)*a(n2)=0.  R. J. Mathar, Jan 14 2020
a(n) = (1)^(n+1)*(n+1)*Sum_{k=1..n} A094485(n,k)*Bernoulli(k). The inverse of the Worpitzky representation of the Bernoulli numbers.  Peter Luschny, May 28 2020
Sum_{n>=1} 1/a(n) = Ei(1)  gamma = A229837.
Sum_{n>=1} (1)^(n+1)/a(n) = gamma  Ei(1) = A239069. (End)


EXAMPLE

E_1(x) + gamma + log(x) = x/1  x^2/4 + x^3/18  x^4/96 + ..., x > 0.  Michael Somos, Dec 11 2002
G.f. = x + 4*x^2 + 18*x^3 + 96*x^4 + 600*x^5 + 4320*x^6 + 35280*x^7 + 322560*x^8 + ...


MAPLE



MATHEMATICA



PROG

(PARI) {a(n) = if( n<0, 0, n * n!)} /* Michael Somos, Dec 11 2002 */
(Haskell)
a001563 n = a001563_list !! n
a001563_list = zipWith () (tail a000142_list) a000142_list
(Magma) [Factorial(n+1)Factorial(n): n in [0..20]]; // Vincenzo Librandi, Aug 08 2014
(Sage) [n*factorial(n) for n in (0..20)] # G. C. Greubel, Dec 30 2019
(GAP) List([0..20], n> n*Factorial(n) ); // G. C. Greubel, Dec 30 2019


CROSSREFS

Cf. sequences with formula (n + k)*n! listed in A282466.


KEYWORD

nonn,easy,nice


AUTHOR



STATUS

approved



