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 A379886 #8 Jan 05 2025 09:57:34
%S A379886 1,2,15,247,6221,212421,9181555,480780875,29589829785,2093629793113,
%T A379886 167458531710431,14942213260220247,1471585837443194533,
%U A379886 158562898380718019813,18555214181719160291403,2343490814996151816116131,317730224718816177328965425,46028095309438150072340711601
%N A379886 E.g.f. A(x) satisfies A(x) = 1/(exp(-x) - x*A(x)^2).
%F A379886 a(n) = n! * Sum_{k=0..n} (3*n-3*k+1)^(k-1) * binomial(3*n-3*k+1,n-k)/k!.
%o A379886 (PARI) a(n) = n!*sum(k=0, n, (3*n-3*k+1)^(k-1)*binomial(3*n-3*k+1, n-k)/k!);
%Y A379886 Cf. A377891, A377893, A379867.
%K A379886 nonn
%O A379886 0,2
%A A379886 _Seiichi Manyama_, Jan 05 2025