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 A372091 #9 Apr 18 2024 09:29:08
%S A372091 1,3,30,378,5382,82377,1323153,21998493,375346062,6534966438,
%T A372091 115634273139,2073448947960,37593341804520,688026597386004,
%U A372091 12694000438662381,235845671565830850,4408763725976408766,82861865131590443808,1564885072909535335695
%N A372091 G.f. A(x) satisfies A(x) = 1/( 1 - 9*x*A(x)*(1 + x*A(x)) )^(1/3).
%F A372091 a(n) = (1/(n+1)) * Sum_{k=0..n} 9^k * binomial(n/3+k-2/3,k) * binomial(k,n-k).
%F A372091 a(n) = 9^n*binomial((4*n-2)/3, n)*hypergeom([(1-n)/2, -n/2], [(2-4*n)/3], -4/9)/(n+1). - _Stefano Spezia_, Apr 18 2024
%o A372091 (PARI) a(n) = sum(k=0, n, 9^k*binomial(n/3+k-2/3, k)*binomial(k, n-k))/(n+1);
%Y A372091 Cf. A372004.
%K A372091 nonn
%O A372091 0,2
%A A372091 _Seiichi Manyama_, Apr 17 2024