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 A177805 #12 Jun 06 2021 06:30:56 %S A177805 1,2,4,7,8,14,16,28,32,49,56,64,98,112,128,136,196,224,256,272,343, %T A177805 392,448,452,512,544,686,784,812,896,904,952,1024,1088,1372,1568,1624, %U A177805 1792,1808,1904,2048,2176,2312,2401,2744,3136,3164,3248,3584,3616,3808,4096 %N A177805 Numbers k such that k divides 15^k - 1. %C A177805 A000420 are the only odd terms of the sequence. - _Robert Israel_, Feb 25 2020 %H A177805 Robert Israel, <a href="/A177805/b177805.txt">Table of n, a(n) for n = 1..2500</a> %p A177805 filter:= n -> 15 &^ n - 1 mod n = 0: %p A177805 select(filter, [$1..10000]); # _Robert Israel_, Feb 25 2020 %o A177805 (PARI) is(n)=Mod(15,n)^n==1 \\ _Charles R Greathouse IV_, Nov 04 2016 %Y A177805 Cf. A000420, A014960, A014956, A014951, A014949, A014946, A014945, A067945, A128358, A128360. %Y A177805 Contains A003591. %K A177805 nonn %O A177805 1,2 %A A177805 _Alexander Adamchuk_, May 17 2010