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 A359649 #7 Jan 08 2024 07:58:41 %S A359649 1,1,5,28,609,6501,272701,4286815,272156417,5648748355,484054204501, %T A359649 12482361156398,1351553781736225,41650209565275195, %U A359649 5460281206077347469,195722005810272604876,30156361094764202326017,1232550298298392183231275,218366864894707599746619685 %N A359649 a(n) = hypergeom([(1 - n)/2, -n/2], [2], 4*n^2). %F A359649 a(n) = p(n, n), where p(n, x) = hypergeom([(1 - n)/2, -n/2], [2], (2*x)^2) are the Motzkin polynomials A359364. %F A359649 a(n) ~ (exp(1) + (-1)^n) * 2^(n + 1/2) * n^(n - 3/2) / (sqrt(Pi) * exp(1/2)). - _Vaclav Kotesovec_, Jan 08 2024 %p A359649 a := n -> hypergeom([(1 - n)/2, -n/2], [2], 4*n^2): %p A359649 seq(simplify(a(n)), n = 0..18); %Y A359649 Cf. A359364. %K A359649 nonn %O A359649 0,3 %A A359649 _Peter Luschny_, Jan 10 2023