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 A366180 #9 Oct 03 2023 09:00:12
%S A366180 1,3,15,109,909,8184,77626,764226,7735878,80011063,841875232,
%T A366180 8983175079,96977392945,1057262750608,11623867926024,128730566729686,
%U A366180 1434752590885174,16080839356274157,181135636330594960,2049430159361529977,23280997677471432102
%N A366180 G.f. A(x) satisfies A(x) = 1/(1 - x)^2 + x*A(x)^3/(1 - x)^3.
%F A366180 a(n) = Sum_{k=0..n} binomial(n+6*k+1,n-k) * binomial(3*k,k)/(2*k+1).
%o A366180 (PARI) a(n) = sum(k=0, n, binomial(n+6*k+1, n-k)*binomial(3*k, k)/(2*k+1));
%Y A366180 Partial sums give A366182.
%Y A366180 Cf. A364620, A364629, A366179.
%K A366180 nonn
%O A366180 0,2
%A A366180 _Seiichi Manyama_, Oct 03 2023