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 A358499 #14 Nov 24 2022 04:22:10
%S A358499 1,1,2,6,25,121,722,5046,40345,363001,3629522,39921846,479041945,
%T A358499 6227383801,87181920722,1307714289846,20923268929945,355693655479801,
%U A358499 6402460887648722,121646408123121846,2432922931445569945,51091297865364919801,1124007130238495328722
%N A358499 a(n) = Sum_{k=0..floor(n/4)} (n-4*k)!.
%H A358499 Seiichi Manyama, <a href="/A358499/b358499.txt">Table of n, a(n) for n = 0..449</a>
%F A358499 a(n) = n * a(n-1) + a(n-4) - n * a(n-5) for n > 4.
%F A358499 a(n) ~ n! * (1 + 1/n^4 + 6/n^5 + 25/n^6 + 90/n^7 + 302/n^8 + 994/n^9 + 3487/n^10 + ...), for coefficients see A099948. - _Vaclav Kotesovec_, Nov 24 2022
%o A358499 (PARI) a(n) = sum(k=0, n\4, (n-4*k)!);
%Y A358499 Cf. A136580, A358498, A358500.
%K A358499 nonn,easy
%O A358499 0,3
%A A358499 _Seiichi Manyama_, Nov 19 2022