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 A377960 #7 Nov 12 2024 11:37:47
%S A377960 1,4,17,82,469,3176,24829,219262,2157257,23405644,277601161,
%T A377960 3572553194,49576701277,737902011952,11725479449909,198112664861206,
%U A377960 3546412902136849,67047080265355412,1334894917247980417,27917550541234128514,611874855066753173861,14024463626236493578744
%N A377960 Expansion of e.g.f. exp(x - x^2)/(1 - x)^3.
%F A377960 a(n) = n! * Sum_{k=0..n} binomial(n-2*k+2,n-k) / k!.
%F A377960 a(n) = (n+3)*a(n-1) - 3*(n-1)*a(n-2) + 2*(n-1)*(n-2)*a(n-3) for n > 2.
%o A377960 (PARI) a(n) = n!*sum(k=0, n, binomial(n-2*k+2, n-k)/k!);
%Y A377960 Cf. A293604, A377958, A377959.
%Y A377960 Cf. A377955.
%K A377960 nonn
%O A377960 0,2
%A A377960 _Seiichi Manyama_, Nov 12 2024