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 A357570 #31 Feb 15 2023 09:41:00
%S A357570 1,1,1,1,1,2,3,4,5,6,9,14,21,30,41,60,93,146,225,336,509,798,1281,
%T A357570 2060,3261,5154,8273,13536,22365,36806,60369,99588,166301,280650,
%U A357570 474801,802424,1358973,2317806,3987185,6893196,11933949,20690738,36022161,63107520,111146141,196322454,347412753
%N A357570 a(n) = Sum_{k=0..floor(n/5)} (n-4*k)!/(n-5*k)!.
%H A357570 Seiichi Manyama, <a href="/A357570/b357570.txt">Table of n, a(n) for n = 0..1000</a>
%F A357570 D-finite with recurrence a(n) = (4 * a(n-1) + n * a(n-5) + 1)/5 for n > 4.
%o A357570 (PARI) a(n) = sum(k=0, n\5, (n-4*k)!/(n-5*k)!);
%Y A357570 Cf. A072374, A122852, A357532, A357533.
%K A357570 nonn,easy
%O A357570 0,6
%A A357570 _Seiichi Manyama_, Nov 19 2022