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 A370930 #12 Mar 06 2024 07:59:51
%S A370930 1,1,4,33,408,6735,139680,3494715,102486720,3448812465,131019940800,
%T A370930 5547190409145,259025571826560,13225167056035935,733000949195074560,
%U A370930 43830500433645600675,2812624056522882201600,192798872614347464289825
%N A370930 Expansion of e.g.f. (1/x) * Series_Reversion( x*(1 - x*exp(x^2/2)) ).
%H A370930 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A370930 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (n-2*k)^k * (2*n-2*k)!/(2^k * k! * (n-2*k)!).
%o A370930 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(serreverse(x*(1-x*exp(x^2/2)))/x))
%o A370930 (PARI) a(n) = sum(k=0, n\2, (n-2*k)^k*(2*n-2*k)!/(2^k*k!*(n-2*k)!))/(n+1);
%Y A370930 Cf. A213644, A370931.
%Y A370930 Cf. A358264.
%K A370930 nonn
%O A370930 0,3
%A A370930 _Seiichi Manyama_, Mar 06 2024