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 A379699 #10 Dec 30 2024 10:50:22
%S A379699 1,3,27,430,10013,309146,11932303,553740958,30053978361,1868855561938,
%T A379699 131048808861491,10232894227577462,880688476587319573,
%U A379699 82836081054992159194,8454536286883278469431,930656450818831650930766,109910217042754940709650417,13862746369348872200671305890
%N A379699 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-x) / (1 + 2*x*exp(x)) ).
%F A379699 a(n) = (n!/(n+1)) * Sum_{k=0..n} 2^(n-k) * (2*n-k+1)^k * binomial(n+1,n-k)/k!.
%o A379699 (PARI) a(n) = n!*sum(k=0, n, 2^(n-k)*(2*n-k+1)^k*binomial(n+1, n-k)/k!)/(n+1);
%Y A379699 Cf. A201470, A377373.
%Y A379699 Cf. A379456, A379700.
%K A379699 nonn
%O A379699 0,2
%A A379699 _Seiichi Manyama_, Dec 30 2024