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 A373771 #8 Jun 18 2024 10:02:04
%S A373771 1,1,3,18,147,1425,15855,200130,2838465,44767485,777046095,
%T A373771 14705245170,301014595035,6621102973485,155640761791515,
%U A373771 3891902825660850,103115436832433025,2884715829245475225,84950805438277854075,2626194012669689512050
%N A373771 Expansion of e.g.f. exp(x^2 / (2 * (1 - x)^3)) / (1 - x).
%F A373771 a(n) = n! * Sum_{k=0..floor(n/2)} binomial(n+k,n-2*k)/(2^k * k!).
%o A373771 (PARI) a(n) = n!*sum(k=0, n\2, binomial(n+k, n-2*k)/(2^k*k!));
%Y A373771 Cf. A130905, A361596, A373770.
%Y A373771 Cf. A361597, A361599.
%Y A373771 Cf. A335345.
%K A373771 nonn
%O A373771 0,3
%A A373771 _Seiichi Manyama_, Jun 18 2024