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 A129496 #10 Jul 24 2021 05:41:03 %S A129496 10,15,21,30,35,38,42,45,46,58,60,62,70,74,82,84,86,90,94,105,106,118, %T A129496 122,126,132,134,140,142,146,158,166,178,180,182,185,190,194,202,206, %U A129496 210,214,215,217,218,219,222,226,228,231,237,249,252,254,258,259,262 %N A129496 Composite numbers k such that 6^k (mod k) is a power of 6 greater than 1. %H A129496 Amiram Eldar, <a href="/A129496/b129496.txt">Table of n, a(n) for n = 1..10000</a> %e A129496 38 is a member of the sequence since 6^38 (mod 38) == 36. %t A129496 Select[Range@ 266, (p = PowerMod[6, #, #]) > 1 && IntegerQ@ Log[6, p] && CompositeQ[#] &] (* corrected by _Amiram Eldar_, Jul 24 2021 *) %Y A129496 Cf. A036236, A129492, A129493, A129494, A129495, A129497. %K A129496 easy,nonn %O A129496 1,1 %A A129496 _Robert G. Wilson v_, Apr 17 2007