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 A371430 #10 Mar 23 2024 10:58:14
%S A371430 1,4,21,128,851,5984,43759,329396,2535406,19863592,157874971,
%T A371430 1269833668,10316765299,84540929568,697928139977,5799156785376,
%U A371430 48461097907978,407020852551016,3434002483872566,29090171931564848,247333930963224287,2109921586071433064
%N A371430 Expansion of (1/x) * Series_Reversion( x / ((1+x)^4 - x^2) ).
%H A371430 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A371430 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (-1)^k * binomial(n+1,k) * binomial(4*n-4*k+4,n-2*k).
%o A371430 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^4-x^2))/x)
%o A371430 (PARI) a(n) = sum(k=0, n\2, (-1)^k*binomial(n+1, k)*binomial(4*n-4*k+4, n-2*k))/(n+1);
%Y A371430 Cf. A317133, A369156.
%Y A371430 Cf. A369213.
%K A371430 nonn
%O A371430 0,2
%A A371430 _Seiichi Manyama_, Mar 23 2024