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 A378151 #10 Nov 18 2024 07:33:10
%S A378151 1,0,0,1,3,3,4,18,45,72,153,450,1066,2172,5142,13381,31752,72333,
%T A378151 176475,441909,1065528,2551465,6292857,15620439,38229235,93698523,
%U A378151 232545105,578019090,1430290512,3548336724,8851036863,22092054588,55093739760,137681640450
%N A378151 G.f. A(x) satisfies A(x) = 1 + (x * (1+x) * A(x))^3.
%F A378151 a(n) = Sum_{k=0..floor(n/3)} binomial(3*k,n-3*k) * binomial(3*k,k)/(2*k+1).
%o A378151 (PARI) a(n) = sum(k=0, n\3, binomial(3*k, n-3*k)*binomial(3*k, k)/(2*k+1));
%Y A378151 Cf. A000045, A256169, A378152.
%Y A378151 Cf. A115055, A378153.
%K A378151 nonn
%O A378151 0,5
%A A378151 _Seiichi Manyama_, Nov 18 2024