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 A379022 #9 Dec 14 2024 07:10:34
%S A379022 1,4,36,370,4012,44824,510498,5892310,68684540,806715964,9532070396,
%T A379022 113179713046,1349276883346,16140148109960,193629588953214,
%U A379022 2328744593780590,28068490664161756,338960821947139640,4100329281075440400,49676100591186493156,602654837914634224812
%N A379022 a(n) = Sum_{k=0..n} binomial(2*n+k-1,k) * binomial(2*n+k,n-k).
%F A379022 a(n) = [x^n] ( (1 + x)/(1 - x - x^2) )^(2*n).
%o A379022 (PARI) a(n) = sum(k=0, n, binomial(2*n+k-1, k)*binomial(2*n+k, n-k));
%Y A379022 Cf. A262910, A379025, A379026.
%Y A379022 Cf. A379021.
%K A379022 nonn
%O A379022 0,2
%A A379022 _Seiichi Manyama_, Dec 14 2024