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 A371609 #12 Mar 30 2024 02:37:03
%S A371609 1,2,5,22,94,452,2253,11640,61732,333924,1836052,10229434,57628078,
%T A371609 327711260,1878658490,10845298128,62993496588,367874945560,
%U A371609 2158717741928,12722258713956,75269561054412,446891212180568,2661788871400197,15900644226590952,95240143776976144
%N A371609 G.f. satisfies A(x) = ( 1 + x * (1 + x*A(x)^2)^2 )^2.
%F A371609 a(n) = Sum_{k=0..n} binomial(4*(n-k)+2,k) * binomial(2*k,n-k)/(2*(n-k)+1).
%F A371609 G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A137955.
%o A371609 (PARI) a(n, r=2, s=2, t=0, u=4) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(s*k, n-k)/(t*k+u*(n-k)+r));
%Y A371609 Cf. A137955, A371614.
%K A371609 nonn
%O A371609 0,2
%A A371609 _Seiichi Manyama_, Mar 29 2024