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 A371362 #10 Mar 20 2024 09:35:32
%S A371362 1,4,31,298,3199,36742,441748,5489554,69945295,908836768,11996580199,
%T A371362 160418984656,2168512922692,29584600414168,406823494817560,
%U A371362 5632906243123090,78465351036084655,1098851032467132484,15461857967408794333,218490450548650811914
%N A371362 Expansion of (1/x) * Series_Reversion( x * (1-3*x)^2 / (1-2*x) ).
%H A371362 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A371362 a(n) = (1/(n+1)) * Sum_{k=0..n} 2^(n-k) * binomial(2*n+k+1,k) * binomial(2*n,n-k).
%o A371362 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-3*x)^2/(1-2*x))/x)
%o A371362 (PARI) a(n) = sum(k=0, n, 2^(n-k)*binomial(2*n+k+1, k)*binomial(2*n, n-k))/(n+1);
%Y A371362 Cf. A007564, A371363.
%K A371362 nonn
%O A371362 0,2
%A A371362 _Seiichi Manyama_, Mar 19 2024