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 A377967 #9 May 28 2025 17:23:56
%S A377967 1,4,19,124,961,8236,79339,840484,9595009,117764596,1542837091,
%T A377967 21406165804,313381177729,4822681240924,77704955681851,
%U A377967 1307128152596116,22899018541506049,416756647023727204,7863586717014612019,153550319029835965276,3097694623619639050561
%N A377967 Expansion of e.g.f. (1+x)^3 * exp(x*(1+x)^3).
%F A377967 a(n) = n! * Sum_{k=0..n} binomial(3*k+3,n-k) / k!.
%t A377967 With[{nn=20},CoefficientList[Series[(1+x)^3 Exp[x*(1+x)^3],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, May 28 2025 *)
%o A377967 (PARI) a(n, s=3, t=3) = n!*sum(k=0, n, binomial(t*k+s, n-k)/k!);
%Y A377967 Cf. A361279, A377964, A377966.
%Y A377967 Cf. A351767.
%K A377967 nonn,easy
%O A377967 0,2
%A A377967 _Seiichi Manyama_, Nov 12 2024