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 A380829 #9 Feb 05 2025 09:23:02
%S A380829 1,4,45,891,25757,986653,47235873,2718521725,182963698521,
%T A380829 14107443728553,1226582182222469,118751669770995913,
%U A380829 12671598073554789909,1477709279563430592877,186988047586389278202633,25518989446806209718773157,3736444151435292273253963313,584269287631534621583659461841
%N A380829 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-3*x) / (1 + x*exp(-x)) ).
%H A380829 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A380829 E.g.f. A(x) satisfies A(x) = exp(3*x*A(x)) / ( 1 - x*exp(2*x*A(x)) ).
%F A380829 a(n) = n! * Sum_{k=0..n} (2*n+k+3)^k * binomial(n,k)/(k+1)!.
%o A380829 (PARI) a(n) = n!*sum(k=0, n, (2*n+k+3)^k*binomial(n, k)/(k+1)!);
%Y A380829 Cf. A361182, A380826, A380830.
%K A380829 nonn
%O A380829 0,2
%A A380829 _Seiichi Manyama_, Feb 05 2025