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 A358606 #15 Nov 28 2022 12:05:33
%S A358606 1,1,1,1,1,0,-1,-2,-3,-4,-3,0,5,12,21,26,21,0,-43,-114,-195,-244,-195,
%T A358606 42,581,1440,2421,2990,2157,-1644,-9955,-22974,-37515,-44248,-24219,
%U A358606 50310,205661,442140,689997,740906,190245,-1534224,-4941355,-9887058,-14429619,-13255900,3510141
%N A358606 a(n) = Sum_{k=0..floor(n/5)} (-1)^k * (n-4*k)!/(n-5*k)!.
%H A358606 Seiichi Manyama, <a href="/A358606/b358606.txt">Table of n, a(n) for n = 0..1000</a>
%F A358606 a(n) = (4 * a(n-1) - n * a(n-5) + 1)/5 for n > 4.
%o A358606 (PARI) a(n) = sum(k=0, n\5, (-1)^k*(n-4*k)!/(n-5*k)!);
%Y A358606 Cf. A358603, A358604, A358605.
%Y A358606 Cf. A357570.
%K A358606 sign
%O A358606 0,8
%A A358606 _Seiichi Manyama_, Nov 23 2022