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 A379327 #9 Dec 21 2024 11:10:08
%S A379327 1,2,6,22,88,372,1634,7382,34078,160034,762078,3671178,17858476,
%T A379327 87599696,432804190,2151867226,10758455224,54053627604,272780539742,
%U A379327 1382047628514,7027307040920,35848334763884,183417043984246,941007480667474,4839875674661214,24950493967407850
%N A379327 G.f. A(x) satisfies A(x) = sqrt( (1 + 2*x*A(x)^2) * (1 + 2*x*A(x)) ).
%F A379327 a(n) = 2^n * Sum_{k=0..n} binomial(n/2+k/2+1/2,k) * binomial(n/2+k/2+1/2,n-k)/(n+k+1).
%o A379327 (PARI) a(n) = 2^n*sum(k=0, n, binomial(n/2+k/2+1/2, k)*binomial(n/2+k/2+1/2, n-k)/(n+k+1));
%Y A379327 Cf. A379326, A379328.
%Y A379327 Cf. A007863, A379279.
%K A379327 nonn
%O A379327 0,2
%A A379327 _Seiichi Manyama_, Dec 21 2024