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 A375172 #16 Aug 06 2024 09:17:23
%S A375172 1,1,4,30,276,2940,36120,507360,8032080,141235920,2725107840,
%T A375172 57151211040,1293129351360,31376876731200,812303844992640,
%U A375172 22338850742208000,650081402588217600,19951131574037664000,643805564147435289600,21785365857810973017600
%N A375172 Expansion of e.g.f. exp( x^2/(1-x)^3 ) / (1-x).
%F A375172 a(n) = n! * Sum_{k=0..floor(n/2)} binomial(n+k,n-2*k)/k!.
%o A375172 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x^2/(1-x)^3)/(1-x)))
%o A375172 (PARI) a(n) = n!*sum(k=0, n\2, binomial(n+k, n-2*k)/k!);
%Y A375172 Cf. A375224, A375225.
%Y A375172 Cf. A361595, A361599.
%K A375172 nonn
%O A375172 0,3
%A A375172 _Seiichi Manyama_, Aug 06 2024