A129247 Invert transform of the Bell numbers.
1, 1, 3, 10, 36, 138, 560, 2402, 10898, 52392, 267394, 1450790, 8371220, 51327178, 333759746, 2295276480, 16639104002, 126718172670, 1010487248556, 8411744415418, 72899055533482, 656136245454232, 6120474697035762
Offset: 0
Keywords
Examples
We have Bell(i) types of an integer i with i=1,2,...,n, where Bell(i) is the i-th Bell number. We write i_j for integer i of type j. a(2)=3 because of the 3 ordered arrangements {1_1,1_1} {2_1}, {2_2}. a(3)=10 because of the 10 ordered arrangements {1_1,1_1,1_1}, {1_1,2_1}, {2_1,1_1}, {1_1,2_2}, {2_2,1_1} {3_1}, {3_2}, {3_3}, {3_4}, {3_5}.
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..576
- M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210; arXiv:math/0205301 [math.CO], 2002.
- M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
- T. Mansour and M. Shattuck, A statistic on n-color compositions and related sequences, Proc. Indian Acad. Sci. (Math. Sci.) 124(2) (2014), pp. 127-140.
- N. J. A. Sloane, Transforms
Programs
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Maple
A129247 := proc(n) option remember ; local i ; if n <= 1 then 1 ; else add(combinat[bell](i)*procname(n-i),i=1..n) ; fi ; end: for n from 0 to 40 do printf("%d,",A129247(n)) ; od: # R. J. Mathar, Aug 25 2008
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Mathematica
a[0] = 1; a[n_] := a[n] = Sum[BellB[i]*a[n - i], {i, 1, n}]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Nov 09 2017 *)
Formula
a(n) = Sum_{i=1..n} Bell(i)*a(n-i).
G.f.: 1/(U(0) - 2*x) where U(k) = 1 - x*(k+1)/(1 - x/U(k+1)); (continued fraction, 2-step). - Sergei N. Gladkovskii, Nov 12 2012
G.f.: 1/( Q(0) - 2*x ) where Q(k) = 1 + x/(x*k - 1 )/Q(k+1); (continued fraction). - Sergei N. Gladkovskii, Feb 23 2013
G.f.: 1/(Q(0) - x), where Q(k) = 1 - x - x/(1 - x*(2*k+1)/(1 - x - x/(1 - 2*x*(k+1)/Q(k+1)))); (continued fraction). - Sergei N. Gladkovskii, May 12 2013
Extensions
Extended by R. J. Mathar, Aug 25 2008
a(0)=1 prepended by Alois P. Heinz, Sep 22 2017
Comments