OFFSET
1,2
LINKS
J.-M. Sixdeniers, K. A. Penson and A. I. Solomon, Extended Bell and Stirling Numbers From Hypergeometric Exponentiation, J. Integer Seqs. Vol. 4 (2001), #01.1.4.
FORMULA
a(n) = A000172(n)/2-1. - Vladeta Jovovic, Apr 23 2003
Sum_{n>=1} a(n) * x^n / (n!)^3 = (1/2) * ( Sum_{n>=1} x^n / (n!)^3 )^2. - Ilya Gutkovskiy, Mar 04 2021
MATHEMATICA
a[n_] := Sum[Binomial[n, k]^3, {k, 0, n}]/2 - 1;
a[n_] := n^2*HypergeometricPFQ[{1 - n, 1 - n, 1 - n}, {2, 2}, -1] - 1;
Table[a[n], {n, 1, 20}] (* Peter Luschny, Apr 17 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 19 2001
STATUS
approved