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 A371538 #10 Mar 27 2024 08:53:18
%S A371538 1,3,18,151,1440,14835,160793,1806849,20859129,245905348,2947869600,
%T A371538 35825319390,440372147956,5465555197818,68396554601013,
%U A371538 862066323857486,10933638171672105,139439595024315675,1787056241039876890,23003636498360053905,297283046361025602900
%N A371538 G.f. A(x) satisfies A(x) = (1 + x*A(x)^2 / (1+x))^3.
%F A371538 a(n) = 3 * Sum_{k=0..n} (-1)^(n-k) * binomial(n-1,n-k) * binomial(6*k+3,k)/(6*k+3).
%F A371538 G.f.: A(x) = B(x)^3 where B(x) is the g.f. of A349362.
%o A371538 (PARI) a(n) = 3*sum(k=0, n, (-1)^(n-k)*binomial(n-1, n-k)*binomial(6*k+3, k)/(6*k+3));
%Y A371538 Cf. A349362, A371537, A371539, A371540, A371541.
%Y A371538 Cf. A371522.
%K A371538 nonn
%O A371538 0,2
%A A371538 _Seiichi Manyama_, Mar 26 2024