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 A370984 #7 Mar 07 2024 01:30:40
%S A370984 1,0,2,6,84,860,14430,257082,5678456,140241096,3952791450,
%T A370984 123539438990,4266378769092,160943793753756,6592371152535350,
%U A370984 291260465060881890,13809548247503299440,699362685890810753552,37679514498664685654706
%N A370984 Expansion of e.g.f. (1/x) * Series_Reversion( x*(1 - x^2*exp(x)) ).
%H A370984 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A370984 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} k^(n-2*k) * (n+k)!/(k! * (n-2*k)!).
%o A370984 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(serreverse(x*(1-x^2*exp(x)))/x))
%o A370984 (PARI) a(n) = sum(k=0, n\2, k^(n-2*k)*(n+k)!/(k!*(n-2*k)!))/(n+1);
%Y A370984 Cf. A213644, A370985.
%Y A370984 Cf. A358080, A370927.
%K A370984 nonn
%O A370984 0,3
%A A370984 _Seiichi Manyama_, Mar 06 2024