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 A377581 #7 Nov 02 2024 09:13:00
%S A377581 1,1,2,27,340,6485,156486,4532647,155359016,6116223465,272369488330,
%T A377581 13537882005131,742838308204092,44605728508797469,2909444391161677838,
%U A377581 204844046364505460655,15484082153045052133456,1250714994867101307618257,107511883999692161772696210
%N A377581 E.g.f. satisfies A(x) = 1 + x * exp(x*A(x)^4).
%F A377581 a(n) = n! * Sum_{k=0..n} k^(n-k) * binomial(4*n-4*k+1,k)/( (4*n-4*k+1)*(n-k)! ).
%o A377581 (PARI) a(n) = n!*sum(k=0, n, k^(n-k)*binomial(4*n-4*k+1, k)/((4*n-4*k+1)*(n-k)!));
%Y A377581 Cf. A161631, A364978, A364979.
%Y A377581 Cf. A377579, A377580.
%K A377581 nonn
%O A377581 0,3
%A A377581 _Seiichi Manyama_, Nov 02 2024