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 A201910 #12 Feb 06 2019 10:59:02
%S A201910 1,1,2,0,1,5,4,6,2,3,1,5,3,4,9,1,5,12,8,1,5,8,6,13,14,2,10,16,12,9,11,
%T A201910 4,3,15,7,1,5,6,11,17,9,7,16,4,1,5,2,10,4,20,8,17,16,11,9,22,18,21,13,
%U A201910 19,3,15,6,7,12,14,1,5,25,9,16,22,23,28,24,4
%N A201910 Irregular triangle of 5^k mod prime(n).
%C A201910 Except for the third row, the first term of each row is 1. Many sequences are in this one: starting at A036121 (mod 23) and A070365 (mod 7).
%H A201910 T. D. Noe, <a href="/A201910/b201910.txt">Rows n = 1..60, flattened</a>
%e A201910 The first 9 rows are:
%e A201910 1
%e A201910 1, 2
%e A201910 0
%e A201910 1, 5, 4, 6, 2, 3
%e A201910 1, 5, 3, 4, 9
%e A201910 1, 5, 12, 8
%e A201910 1, 5, 8, 6, 13, 14, 2, 10, 16, 12, 9, 11, 4, 3, 15, 7
%e A201910 1, 5, 6, 11, 17, 9, 7, 16, 4
%e A201910 1, 5, 2, 10, 4, 20, 8, 17, 16, 11, 9, 22, 18, 21, 13, 19, 3, 15, 6, 7, 12, 14
%t A201910 nn = 10; p = 5; t = p^Range[0,Prime[nn]]; Flatten[Table[If[Mod[n, p] == 0, {0}, tm = Mod[t, n]; len = Position[tm, 1, 1, 2][[-1,1]]; Take[tm, len-1]], {n, Prime[Range[nn]]}]]
%o A201910 (GAP) P:=Filtered([1..350],IsPrime);;
%o A201910 R:=List([1..Length(P)],n->OrderMod(5,P[n]));;
%o A201910 Flat(Concatenation([1,1,2,0],List([3..10],n->List([0..R[n]-1],k->PowerMod(5,k,P[n]))))); # _Muniru A Asiru_, Feb 02 2019
%Y A201910 Cf. A201908 (2^k), A201909 (3^k), A201911 (7^k).
%Y A201910 Cf. A070365 (7), A070367 (11), A070368 (13), A070371 (17), A070373 (19), A036121 (23), A070379 (29), A070384 (37), A070387 (41), A070389 (43), A036127 (47), A036133 (73), A036137 (97), A036139 (103), A036149 (157), A036151 (167), A036156 (193).
%K A201910 nonn,tabf
%O A201910 1,3
%A A201910 _T. D. Noe_, Dec 07 2011