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 A379251 #8 Dec 19 2024 10:10:03
%S A379251 1,4,32,340,4144,54724,761712,11004500,163453472,2480507524,
%T A379251 38292849280,599455647828,9493724671184,151835354054212,
%U A379251 2448792546337360,39781755539153748,650386418008379200,10692713526634029316,176669496568313495520,2931998993134971532116,48854054306918652620912
%N A379251 G.f. A(x) satisfies A(x) = ( (1 + x*A(x))/(1 - x*A(x)^2) )^2.
%F A379251 G.f.: B(x)^2 where B(x) is the g.f. of A361638.
%F A379251 a(n) = Sum_{k=0..n} binomial(2*n+3*k+1,k) * binomial(2*n+2*k+2,n-k)/(n+k+1).
%o A379251 (PARI) a(n) = sum(k=0, n, binomial(2*n+3*k+1, k)*binomial(2*n+2*k+2, n-k)/(n+k+1));
%Y A379251 Cf. A006319, A032349, A379252.
%Y A379251 Cf. A361638.
%K A379251 nonn
%O A379251 0,2
%A A379251 _Seiichi Manyama_, Dec 19 2024