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 A380946 #10 Feb 09 2025 09:18:47
%S A380946 1,6,111,3678,179073,11588688,938905551,91542271824,10444685410881,
%T A380946 1365936450693120,201503447217869679,33108736185915906816,
%U A380946 5997057218957213126721,1187319940110958086623232,255104922613608981003351375,59120580081196768991316314112
%N A380946 Expansion of e.g.f. (1/x) * Series_Reversion( x * (1 - x)^3 * exp(-3*x) ).
%H A380946 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A380946 E.g.f. A(x) satisfies A(x) = exp(3*x*A(x))/(1 - x*A(x))^3.
%F A380946 E.g.f.: B(x)^3, where B(x) is the e.g.f. of A380724.
%F A380946 a(n) = 3 * n! * Sum_{k=0..n} (3*n+3)^(k-1) * binomial(4*n-k+2,n-k)/k!.
%o A380946 (PARI) a(n, q=3, r=3, s=3, t=0, u=1) = q*n!*sum(k=0, n, (r*n+(s-r)*k+q)^(k-1)*binomial((r*u+1)*n+((s-r)*u+t-1)*k+q*u-1, n-k)/k!);
%Y A380946 Cf. A370057, A377833.
%Y A380946 Cf. A380647, A380724.
%K A380946 nonn
%O A380946 0,2
%A A380946 _Seiichi Manyama_, Feb 09 2025