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 A376810 #8 Oct 05 2024 02:48:09
%S A376810 1,2,6,24,94,378,1544,6380,26598,111658,471358,1998924,8509368,
%T A376810 36341278,155634228,668116136,2874157222,12387209982,53475080494,
%U A376810 231189987224,1000834283190,4337864724462,18821884379924,81748960355484,355383570351664,1546239230878154
%N A376810 Expansion of 1/sqrt(1 - 4*x/(1 - x^2)^2).
%F A376810 a(n) = Sum_{k=0..floor(n/2)} binomial(2*n-3*k-1,k) * binomial(2*n-4*k,n-2*k).
%o A376810 (PARI) my(N=30, x='x+O('x^N)); Vec(1/sqrt(1-4*x/(1-x^2)^2))
%o A376810 (PARI) a(n) = sum(k=0, n\2, binomial(2*n-3*k-1, k)*binomial(2*n-4*k, n-2*k));
%Y A376810 Cf. A110170, A376811.
%Y A376810 Cf. A349713.
%K A376810 nonn
%O A376810 0,2
%A A376810 _Seiichi Manyama_, Oct 04 2024