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 A371494 #8 Mar 25 2024 09:21:35
%S A371494 1,2,5,18,72,310,1399,6532,31287,152876,759034,3818410,19420713,
%T A371494 99697784,515909606,2688267462,14093211259,74281217492,393389969722,
%U A371494 2092312452404,11171325560120,59854910468196,321717833732186,1734250394445622,9373581927760595
%N A371494 G.f. A(x) satisfies A(x) = 1 / (1 - x*A(x) / (1+x))^2.
%F A371494 a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n-1,n-k) * binomial(3*k+1,k)/(k+1).
%o A371494 (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*binomial(n-1, n-k)*binomial(3*k+1, k)/(k+1));
%Y A371494 Cf. A001006, A371495, A371496.
%Y A371494 Cf. A006013.
%K A371494 nonn
%O A371494 0,2
%A A371494 _Seiichi Manyama_, Mar 25 2024