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 A068382 #21 Apr 04 2020 20:01:05
%S A068382 1,2,4,8,10,16,20,32,40,50,64,80,100,110,128,136,160,164,200,220,250,
%T A068382 256,272,320,328,400,440,500,512,544,550,610,640,656,680,800,820,880,
%U A068382 1000,1024,1088,1100,1210,1220,1250,1280,1312,1360,1544,1600,1640,1760
%N A068382 Numbers k such that k divides 9^k - 1.
%C A068382 For all m the sequence includes 2^m, 10^m, 2*10^m, 10*2^m.
%H A068382 Seiichi Manyama, <a href="/A068382/b068382.txt">Table of n, a(n) for n = 1..5000</a>
%t A068382 Join[{1}, Select[Range[10000], PowerMod[9, #, #] == 1 &]] (* _Robert Price_, Apr 04 2020 *)
%o A068382 (PARI) isok(n) = Mod(9, n)^n == Mod(1, n); \\ _Michel Marcus_, May 06 2016
%Y A068382 Cf. A014945, A014946, A014949, A014950.
%K A068382 easy,nonn
%O A068382 1,2
%A A068382 _Benoit Cloitre_, Mar 05 2002