OFFSET
0,2
COMMENTS
For n>1: a(n) is the number of entries in the last blocks of all set partitions of [n]. a(3) = 8 because the number of entries in the last blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 3+1+1+2+1 = 8. - Alois P. Heinz, May 08 2017
REFERENCES
H. W. Gould, A linear binomial recurrence and the Bell numbers and polynomials, preprint, 1998
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..500
R. K. Guy, Letters to N. J. A. Sloane, June-August 1968
FORMULA
G.f. A(x) satisfies: A(x) = 1 + x * (1 + A(x/(1 - x)) / (1 - x)). - Ilya Gutkovskiy, Jun 30 2020
MAPLE
A038561List := proc(m) local A, P, n; A := [1, 2]; P := [1];
for n from 1 to m - 2 do P := ListTools:-PartialSums([A[-1], op(P)]);
A := [op(A), P[-1]] od; A end: A038561List(24); # Peter Luschny, Mar 24 2022
MATHEMATICA
a[0, 0] = 1; a[1, 0] = 2; a[n_, 0] := a[n-1, n-1]; a[n_, k_] := a[n, k] = a[n, k-1] + a[n-1, k-1]; a[n_] := a[n, 0]; Table[a[n], {n, 0, 23}] (* Jean-François Alcover, Jun 06 2013 *)
PROG
(Haskell)
a038561 = head . a046937_row -- Reinhard Zumkeller, Jan 06 2014
CROSSREFS
KEYWORD
nonn,nice,easy
AUTHOR
STATUS
approved