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 A211243 #21 May 13 2024 09:16:22
%S A211243 1,1,4,0,10,12,16,3,22,7,15,9,40,6,23,26,29,60,66,70,24,78,41,88,96,
%T A211243 100,51,106,27,14,126,65,68,69,74,150,52,162,83,172,178,12,10,24,98,
%U A211243 99,210,37,113,228,116,238,240,125,256,262,268,135,138,20,141,292
%N A211243 Order of 7 mod n-th prime: least k such that prime(n) divides 7^k-1.
%H A211243 T. D. Noe, <a href="/A211243/b211243.txt">Table of n, a(n) for n = 1..1000</a>
%t A211243 nn = 7; Table[If[Mod[nn, p] == 0, 0, MultiplicativeOrder[nn, p]], {p, Prime[Range[100]]}]
%o A211243 (GAP) A000040:=Filtered([1..350],IsPrime);;
%o A211243 List([1..Length(A000040)],n->OrderMod(7,A000040[n])); # _Muniru A Asiru_, Feb 06 2019
%o A211243 (PARI) a(n,{base=7}) = my(p=prime(n)); if(base%p, znorder(Mod(base,p)), 0) \\ _Jianing Song_, May 13 2024
%Y A211243 Cf. A019337 (full reptend primes in base 7).
%Y A211243 In other bases: A014664, A062117, A082654, A211241, A211242, A211244, A211245, A002371.
%Y A211243 Row lengths of A201911. - _Michel Marcus_, Feb 04 2019
%K A211243 nonn,easy
%O A211243 1,3
%A A211243 _T. D. Noe_, Apr 11 2012