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 A217469 #25 Feb 16 2025 08:33:18
%S A217469 2,5,4,6,4,3,6,20,22,16,6,30,10,5,9,54,42,12,8,25,52,36,14,55,6,65,16,
%T A217469 46,72,75,4,66,82,18,20,15,6,19,42,22,102,35,18,16,112,30,29,40,20,25,
%U A217469 64,42,18,27,22,140,20,96,36,42,48,155,39,106,54,165,12,15
%N A217469 Multiplicative order of 5 (mod 5*n + 1).
%C A217469 Least m such that 5*n + 1 divides 5^m - 1.
%H A217469 Arkadiusz Wesolowski, <a href="/A217469/b217469.txt">Table of n, a(n) for n = 1..10000</a>
%H A217469 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativeOrder.html">Multiplicative Order</a>
%t A217469 Table[MultiplicativeOrder[5, 5*n + 1], {n, 68}]
%o A217469 (PARI) vector(80, n, znorder(Mod(5, 5*n+1))) \\ _Michel Marcus_, Feb 09 2015
%o A217469 (GAP) List([1..80],n->OrderMod(5,5*n+1)); # _Muniru A Asiru_, Feb 26 2019
%Y A217469 Cf. A002326, A003571, A003573.
%K A217469 nonn
%O A217469 1,1
%A A217469 _Arkadiusz Wesolowski_, Nov 16 2012