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 A379701 #9 Dec 30 2024 11:24:07
%S A379701 1,0,3,2,113,304,13747,83600,3590337,38193920,1650383171,26535997696,
%T A379701 1186785903217,26244849422336,1234578346302771,35176362803984384,
%U A379701 1757110507998276353,61533880908307038208,3281634015502670522371,136392534106346468999168
%N A379701 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(x) / (1 + x*exp(2*x)) ).
%F A379701 a(n) = (n!/(n+1)) * Sum_{k=0..n} (n-2*k-1)^k * binomial(n+1,n-k)/k!.
%o A379701 (PARI) a(n) = n!*sum(k=0, n, (n-2*k-1)^k*binomial(n+1, n-k)/k!)/(n+1);
%Y A379701 Cf. A108919, A379702.
%Y A379701 Cf. A366232.
%K A379701 nonn
%O A379701 0,3
%A A379701 _Seiichi Manyama_, Dec 30 2024