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 A380826 #14 Feb 05 2025 09:22:58
%S A380826 1,4,43,810,22273,811728,36979467,2025462736,129748802401,
%T A380826 9522843081984,788169731306059,72641846664240384,7379343546762675873,
%U A380826 819269203286474309632,98698960328223628470379,12824232015954542746048512,1787731339345567827140060737,266157254062414638948185210880
%N A380826 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-3*x) / (1 + x*exp(-2*x)) ).
%H A380826 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A380826 E.g.f. A(x) satisfies A(x) = exp(3*x*A(x)) / ( 1 - x*exp(x*A(x)) ).
%F A380826 a(n) = n! * Sum_{k=0..n} (n+2*k+3)^k * binomial(n,k)/(k+1)!.
%o A380826 (PARI) a(n) = n!*sum(k=0, n, (n+2*k+3)^k*binomial(n, k)/(k+1)!);
%Y A380826 Cf. A088690, A161633, A380808.
%Y A380826 Cf. A361182, A380829, A380830.
%K A380826 nonn
%O A380826 0,2
%A A380826 _Seiichi Manyama_, Feb 04 2025