This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A377966 #9 Nov 13 2024 06:49:04
%S A377966 1,3,13,85,621,5131,48553,500613,5590105,67453651,868300581,
%T A377966 11854859413,171122864773,2598083998875,41331779697601,
%U A377966 687151457132101,11904595227392433,214378528158055843,4004773210169606845,77459628036613435221,1548502062887370346141
%N A377966 Expansion of e.g.f. (1+x)^2 * exp(x*(1+x)^3).
%F A377966 a(n) = n! * Sum_{k=0..n} binomial(3*k+2,n-k) / k!.
%o A377966 (PARI) a(n, s=2, t=3) = n!*sum(k=0, n, binomial(t*k+s, n-k)/k!);
%Y A377966 Cf. A377954, A377965.
%Y A377966 Cf. A361279, A377964, A377967.
%K A377966 nonn,easy
%O A377966 0,2
%A A377966 _Seiichi Manyama_, Nov 12 2024