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 A369440 #9 Jan 23 2024 11:14:33
%S A369440 1,1,3,9,30,107,396,1513,5915,23554,95202,389555,1610588,6717816,
%T A369440 28234064,119452553,508330809,2174393331,9343913933,40319400738,
%U A369440 174630125428,758916134002,3308320668768,14462616815619,63388694309005,278492994845776,1226241871745376
%N A369440 Expansion of (1/x) * Series_Reversion( x / ((1+x) * (1+x^2)^2) ).
%H A369440 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369440 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(2*n+2,k) * binomial(n+1,n-2*k).
%o A369440 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)*(1+x^2)^2))/x)
%o A369440 (PARI) a(n, s=2, t=2, u=1) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial(u*(n+1), n-s*k))/(n+1);
%Y A369440 Cf. A036765, A369441.
%K A369440 nonn
%O A369440 0,3
%A A369440 _Seiichi Manyama_, Jan 23 2024