A137341 a(n) = n! * A000110(n) where A000110 is the sequence of Bell numbers.
1, 1, 4, 30, 360, 6240, 146160, 4420080, 166924800, 7673823360, 420850080000, 27086342976000, 2018319704755200, 172142484203289600, 16642276683198566400, 1808459441303074560000, 219273812138054209536000, 29473992420094651613184000
Offset: 0
Keywords
Examples
a(0) = 1; a(1) = C(0,0)*a(0)*1!/0! = 1; a(2) = C(1,1)*a(1)*2!/1! + C(1,0)*a(0)*2!/0! = 4; a(3) = C(2,2)*a(2)*3!/2! + C(2,1)*a(1)*3!/1! + C(2,0)*a(0)*3!/0! = 30; a(4) = C(3,3)*a(3)*4!/3! + C(3,2)*a(2)*4!/2! + C(3,1)*a(1)*4!/1! + C(3,0)*a(0)*4!/0! = 360. From _Olivier Gérard_, Aug 12 2016: (Start) Illustration as family of lists of sublists extending set partitions. In this interpretation the lowercase letters allow us to distinguish between integers introduced at each iteration (or generation). Construction from the family of size n to family of size n+1 is done by insertion. Insertion is only possible at the end of a sublist or to create a new singleton sublist at the end of the list. : 1: {{1a}}* 4: {{1a},{1b}} {{1a,1b}} {{1a,2b}}* {{1a},{2b}}* 30: {{1a,1c},{1b}} {{1a},{1b,1c}} {{1a},{1b},{1c}} ....{{1a,2c},{1b}} {{1a},{1b,2c}} {{1a},{1b},{2c}} ....{{1a,3c},{1b}} {{1a},{1b,3c}} {{1a},{1b},{3c}} ....{{1a,1b,1c}} {{1a,1b},{1c}} ....{{1a,1b,2c}} {{1a,1b},{2c}} ....{{1a,1b,3c}} {{1a,1b},{3c}} ....{{1a,2b,1c}} {{1a,2b,2c}} {{1a,2b,3c}}* ....{{1a,2b},{1c}} {{1a,2b},{2c}} {{1a,2b},{3c}}* ....{{1a,1c},{2b}} {{1a},{2b,1c}} {{1a},{2b},{1c}} ....{{1a,2c},{2b}} {{1a},{2b,2c}} {{1a},{2b},{2c}} ....{{1a,3c},{2b}}* {{1a},{2b,3c}}* {{1a},{2b},{3c}}* : The lists of sublists marked with * correspond to classical set partitions counted by Bell numbers A000110. (End)
References
- W. Lucas and R. Thrall, N-person games in partition function form, Naval Research Logistics Quarterly X, pp. 281-298, 1963.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..200
- E. T. Bell, Exponential numbers, Amer. Math. Monthly, 41 (1934), 411-419.
- Abel Lacabanne, Framization of Schur-Weyl duality and Yokonuma-Hecke type algebras, arXiv:2312.14796 [math.RT], 2023. See p. 34.
- David W. K. Yeung, Eric L. H. Ku and Patricia M. Yeung, A Recursive Sequence for the Number of Positioned Partition, International Journal of Algebra, Vol. 2 (2008), No. 4, pp. 181-185.
Crossrefs
Programs
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Maple
b:= proc(n) option remember; `if`(n=0, 1, add(b(n-j)*binomial(n-1, j-1), j=1..n)) end: a:= n-> b(n)*n!: seq(a(n), n=0..23); # Alois P. Heinz, Aug 30 2019
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Mathematica
Table[n!*BellB[n],{n,0,20}] (* Vaclav Kotesovec, Mar 13 2014 *)
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PARI
Vec(serlaplace(serlaplace(exp(exp(O(x^20)+x)-1)))) \\ Joerg Arndt, Mar 13 2009
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Python
from sympy import bell, factorial [factorial(n) * bell(n) for n in range(101)] # Indranil Ghosh, Mar 20 2017
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Sage
[factorial(m) * bell_number(m) for m in range(17)] # Zerinvary Lajos, Jul 06 2008
Formula
a(0) = 1; for n>0, a(n) = Sum_{j=0..n-1} binomial(n-1,j) * a(j) * n!/j!.
From the recurrence it follows that A'(x) = exp(x) * A(x) where A(x) = Sum_{k>=0} a(k) * x^k / k!^2. The solution to this differential equation is A(x) = exp(exp(x)). The expression in Joerg Arndt's PARI program follows from this. - Max Alekseyev, Mar 11 2009
a(n) ~ n^(2*n+1/2) * exp(n/LambertW(n)-1-2*n) * sqrt(2*Pi/(1+LambertW(n))) / LambertW(n)^n. - Vaclav Kotesovec, Mar 13 2014
a(n) = n! * Sum_{j=0..n} Stirling2(n,j). - Detlef Meya, Apr 11 2024
Extensions
Edited by N. J. A. Sloane, Sep 19 2009
More terms from Vincenzo Librandi, Mar 15 2014
Comments