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 A372013 #13 Apr 19 2024 10:31:14
%S A372013 1,-1,4,-1,46,149,1351,8441,63499,462752,3514807,26923478,209566927,
%T A372013 1647633779,13079663527,104649229988,843120766711,6833665175513,
%U A372013 55683581174641,455878084448132,3748025535972448,30931714278955736,256150668109462507
%N A372013 G.f. A(x) satisfies A(x) = 1/( 1 + x*(1 - 9*x*A(x))^(1/3) ).
%F A372013 a(n) = (-1)^n * Sum_{k=0..n} 9^(n-k) * binomial(n,k) * binomial(k/3,n-k)/(n-k+1).
%o A372013 (PARI) a(n) = (-1)^n*sum(k=0, n, 9^(n-k)*binomial(n, k)*binomial(k/3, n-k)/(n-k+1));
%Y A372013 Cf. A166587, A362155, A372012.
%K A372013 sign
%O A372013 0,3
%A A372013 _Seiichi Manyama_, Apr 19 2024