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 A369439 #8 Jan 23 2024 11:14:38
%S A369439 1,2,6,22,89,382,1708,7870,37108,178184,868318,4283402,21347902,
%T A369439 107330004,543707480,2772469998,14219396908,73303128344,379621891640,
%U A369439 1974078923416,10303600000553,53960438323438,283461807342876,1493252678987602,7886649917261724
%N A369439 Expansion of (1/x) * Series_Reversion( x / ((1+x)^2 * (1+x^2)) ).
%H A369439 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369439 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(n+1,k) * binomial(2*n+2,n-2*k).
%o A369439 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^2*(1+x^2)))/x)
%o A369439 (PARI) a(n, s=2, t=1, u=2) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial(u*(n+1), n-s*k))/(n+1);
%Y A369439 Cf. A036765.
%K A369439 nonn
%O A369439 0,2
%A A369439 _Seiichi Manyama_, Jan 23 2024