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 A371608 #11 Mar 30 2024 02:37:14
%S A371608 1,2,3,14,55,226,1042,4840,23103,113118,561568,2826550,14392534,
%T A371608 73967650,383271596,2000096144,10502029735,55446004880,294155761676,
%U A371608 1567371462762,8384300275607,45009106969022,242400290365756,1309314066314354,7091306989205453
%N A371608 G.f. satisfies A(x) = ( 1 + x * (1 + x*A(x)^3) )^2.
%F A371608 a(n) = Sum_{k=0..n} binomial(6*(n-k)+2,k) * binomial(k,n-k)/(3*(n-k)+1).
%F A371608 G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A137966.
%o A371608 (PARI) a(n, r=2, s=1, t=0, u=6) = 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 A371608 Cf. A137966, A371613.
%K A371608 nonn
%O A371608 0,2
%A A371608 _Seiichi Manyama_, Mar 29 2024