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 A177807 #17 Jun 13 2021 16:57:42
%S A177807 1,2,4,6,8,12,16,18,20,24,32,36,40,42,48,54,60,64,72,78,80,84,96,100,
%T A177807 108,116,120,126,128,144,156,160,162,168,180,192,200,216,220,232,234,
%U A177807 240,252,256,288,294,300,312,320,324,336,342,348,360,378,384,400,420
%N A177807 Numbers k that divide 17^k - 1.
%H A177807 Zizheng Fang, <a href="/A177807/b177807.txt">Table of n, a(n) for n = 1..10000</a>
%H A177807 Zizheng Fang, <a href="/A177807/a177807.txt">Python program to generate A177807</a>
%t A177807 {1}~Join~Select[Range[420], PowerMod[17, #, #] == 1 &] (* _Giovanni Resta_, Jan 30 2020 *)
%Y A177807 Cf. A014960, A014956, A014957, A014951, A014949, A014946, A014945, A067945, A128358, A128360, A177805.
%K A177807 nonn
%O A177807 1,2
%A A177807 _Alexander Adamchuk_, May 17 2010