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 A368962 #18 Jan 13 2024 10:45:13
%S A368962 1,2,7,32,165,910,5251,31314,191463,1193808,7561825,48522630,
%T A368962 314752515,2060587112,13597183916,90342651982,603886553067,
%U A368962 4058197580308,27401404029181,185806213609730,1264774546754103,8639226724499070,59198404680049915
%N A368962 Expansion of (1/x) * Series_Reversion( x * (1-x-x^3)^2 ).
%H A368962 Seiichi Manyama, <a href="/A368962/b368962.txt">Table of n, a(n) for n = 0..1000</a>
%H A368962 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A368962 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(2*n+k+1,k) * binomial(3*n-2*k+1,n-3*k).
%o A368962 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x-x^3)^2)/x)
%o A368962 (PARI) a(n, s=3, t=2, u=0) = sum(k=0, n\s, binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);
%Y A368962 Cf. A368966, A368968.
%Y A368962 Cf. A368961.
%K A368962 nonn
%O A368962 0,2
%A A368962 _Seiichi Manyama_, Jan 10 2024