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 A369159 #9 Jan 15 2024 09:03:32
%S A369159 1,3,12,55,274,1443,7905,44593,257305,1511553,9010170,54361486,
%T A369159 331336454,2037132958,12619056108,78682008194,493427982703,
%U A369159 3110202012353,19693920616872,125214061831251,799059649687239,5116372686471627,32860439054510610
%N A369159 Expansion of (1/x) * Series_Reversion( x / ((1+x)^3+x^4) ).
%H A369159 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369159 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+1,k) * binomial(3*n-3*k+3,n-4*k).
%o A369159 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^3+x^4))/x)
%o A369159 (PARI) a(n) = sum(k=0, n\4, binomial(n+1, k)*binomial(3*n-3*k+3, n-4*k))/(n+1);
%Y A369159 Cf. A127902, A369126, A369158.
%K A369159 nonn
%O A369159 0,2
%A A369159 _Seiichi Manyama_, Jan 15 2024