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 A378462 #6 Nov 27 2024 08:06:49
%S A378462 1,1,5,28,157,891,5126,29814,174869,1032481,6128795,36541220,
%T A378462 218672950,1312712519,7901609196,47673716238,288226881669,
%U A378462 1745734656930,10590673033931,64342403492274,391414638274987,2383907483199039,14534764399148966,88705912126094358
%N A378462 a(n) = Sum_{k=0..floor(n/2)} binomial(n+k-1,k) * binomial(2*n+k-1,n-2*k).
%F A378462 a(n) = [x^n] 1/(1 - x - x^2/(1 - x)^2)^n.
%o A378462 (PARI) a(n) = sum(k=0, n\2, binomial(n+k-1, k)*binomial(2*n+k-1, n-2*k));
%Y A378462 Cf. A002002, A213684.
%Y A378462 Cf. A378467.
%K A378462 nonn
%O A378462 0,3
%A A378462 _Seiichi Manyama_, Nov 27 2024