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 A369081 #9 Jan 13 2024 10:47:50
%S A369081 1,0,0,-3,-3,-3,30,72,123,-313,-1533,-3888,827,28893,107637,116372,
%T A369081 -420813,-2657823,-5660571,1544334,57009453,190508467,207797979,
%U A369081 -955665852,-5323553041,-11293308333,6516682923,125714105729,411566197974,382778797437,-2328595584491
%N A369081 Expansion of (1/x) * Series_Reversion( x * (1+x^3/(1-x))^3 ).
%H A369081 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369081 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^k * binomial(3*n+k+2,k) * binomial(n-2*k-1,n-3*k).
%o A369081 (PARI) my(N=40, x='x+O('x^N)); Vec(serreverse(x*(1+x^3/(1-x))^3)/x)
%o A369081 (PARI) a(n, s=3, 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 A369081 Cf. A179848, A369078.
%Y A369081 Cf. A369014.
%K A369081 sign
%O A369081 0,4
%A A369081 _Seiichi Manyama_, Jan 12 2024