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 A375691 #22 Sep 27 2024 16:33:44
%S A375691 1,0,0,0,1,1,0,0,3,6,3,0,12,36,36,12,55,220,330,220,328,1365,2730,
%T A375691 2730,2793,8841,21420,28560,29172,62832,164220,271320,314583,508896,
%U A375691 1265628,2430480,3275085,4642803,10091664,21066804,32555028,45388200,85102875
%N A375691 G.f. A(x) satisfies A(x) = 1 + x^4*(1+x)*A(x)^3.
%F A375691 a(n) = Sum_{k=0..floor(n/4)} binomial(k,n-4*k) * binomial(3*k,k)/(2*k+1).
%o A375691 (PARI) a(n) = sum(k=0, n\4, binomial(k, n-4*k)*binomial(3*k, k)/(2*k+1));
%Y A375691 Cf. A017827, A366589, A376487, A376546.
%K A375691 nonn
%O A375691 0,9
%A A375691 _Seiichi Manyama_, Sep 27 2024