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 A371434 #11 Mar 23 2024 11:05:30
%S A371434 1,3,14,76,444,2702,16840,106389,676566,4307754,27333384,172040544,
%T A371434 1068547788,6505380072,38446578888,217095119499,1136270066490,
%U A371434 5125578859296,15040187738184,-47786768551830,-1453703259770520,-18311261482519860,-186896777677695720
%N A371434 Expansion of (1/x) * Series_Reversion( x * ((1-x)^3 + x^2) ).
%H A371434 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A371434 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (-1)^k * binomial(n+k,k) * binomial(4*n+k+2,n-2*k).
%o A371434 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*((1-x)^3+x^2))/x)
%o A371434 (PARI) a(n) = sum(k=0, n\2, (-1)^k*binomial(n+k, k)*binomial(4*n+k+2, n-2*k))/(n+1);
%Y A371434 Cf. A371433, A371435.
%Y A371434 Cf. A369694.
%K A371434 sign
%O A371434 0,2
%A A371434 _Seiichi Manyama_, Mar 23 2024