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 A369078 #8 Jan 13 2024 10:47:54
%S A369078 1,0,-3,-3,21,54,-157,-828,816,11684,5352,-151407,-288759,1737498,
%T A369078 6671607,-15789371,-122051205,58021488,1935857500,1977087345,
%U A369078 -26913144267,-70826569596,314853424458,1586212109946,-2594198888498,-29124507344868,-2575010176581
%N A369078 Expansion of (1/x) * Series_Reversion( x * (1+x^2/(1-x))^3 ).
%H A369078 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369078 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (-1)^k * binomial(3*n+k+2,k) * binomial(n-k-1,n-2*k).
%o A369078 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1+x^2/(1-x))^3)/x)
%o A369078 (PARI) a(n, s=2, t=3, u=-3) = sum(k=0, n\s, (-1)^k*binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);
%Y A369078 Cf. A179848, A369081.
%Y A369078 Cf. A369013.
%K A369078 sign
%O A369078 0,3
%A A369078 _Seiichi Manyama_, Jan 12 2024