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 A366697 #9 Oct 17 2023 08:19:27
%S A366697 1,4,15,94,706,5769,49923,449376,4164228,39459852,380594767,
%T A366697 3724049805,36876008673,368835076813,3720863181033,37815675159285,
%U A366697 386818379566749,3979362306753315,41144521893563511,427335033811660713,4456402044181677264
%N A366697 G.f. satisfies A(x) = (1 + x)^3 + x*A(x)^3.
%F A366697 a(n) = Sum_{k=0..n} binomial(3*(2*k+1),n-k) * binomial(3*k,k)/(2*k+1).
%o A366697 (PARI) a(n) = sum(k=0, n, binomial(3*(2*k+1), n-k)*binomial(3*k, k)/(2*k+1));
%Y A366697 Cf. A366266, A366696.
%Y A366697 Cf. A364623.
%K A366697 nonn
%O A366697 0,2
%A A366697 _Seiichi Manyama_, Oct 16 2023