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 A211241 #22 May 13 2024 09:16:15
%S A211241 1,2,0,6,5,4,16,9,22,14,3,36,20,42,46,52,29,30,22,5,72,39,82,44,96,25,
%T A211241 102,106,27,112,42,65,136,69,37,75,156,54,166,172,89,15,19,192,196,33,
%U A211241 35,222,226,114,232,119,40,25,256,262,67,27,276,140,282,292
%N A211241 Order of 5 mod n-th prime: least k such that prime(n) divides 5^k-1.
%H A211241 T. D. Noe, <a href="/A211241/b211241.txt">Table of n, a(n) for n = 1..1000</a>
%H A211241 Alexandre Zalesski, <a href="https://arxiv.org/abs/2401.16075">Unisingular subgroups of symplectic group Sp_2n(2) for 2n < 250</a>, arXiv:2401.16075 [math.GR], 2024. See p. 52.
%t A211241 nn = 5; Table[If[Mod[nn, p] == 0, 0, MultiplicativeOrder[nn, p]], {p, Prime[Range[100]]}]
%o A211241 (GAP) A000040:=Filtered([1..350],IsPrime);;
%o A211241 List([1..Length(A000040)],n->OrderMod(5,A000040[n])); # _Muniru A Asiru_, Feb 06 2019
%o A211241 (PARI) a(n,{base=5}) = my(p=prime(n)); if(base%p, znorder(Mod(base,p)), 0) \\ _Jianing Song_, May 13 2024
%Y A211241 Cf. A019335 (full reptend primes in base 5).
%Y A211241 In other bases: A014664, A062117, A082654, A211242, A211243, A211244, A211245, A002371.
%K A211241 nonn,easy
%O A211241 1,2
%A A211241 _T. D. Noe_, Apr 11 2012