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 A066501 #17 Feb 10 2021 21:00:11
%S A066501 1,2,3,4,5,6,10,11,17,22,23,25,29,34,41,46,47,50,53,58,59,71,82,83,89,
%T A066501 94,101,106,107,113,118,121,125,131,137,142,149,166,167,173,178,179,
%U A066501 191,197,202,214,226,227,233,239,242,250,251,257,262,263,269,274,281,289,293
%N A066501 Numbers k such that x^6 == 1 (mod(k)) has no solution 1 < x < k-1.
%F A066501 Sequence consists of the numbers 4, 6 and for all k > 1, A045309(k), 2*A045309(k), A045309(k)^2, 2*A045309(k)^2.
%o A066501 (PARI) isok(n) = {for (x=2, n-2, if ((Mod(x, n)^6) == Mod(1, n), return (0));); return (1);} \\ _Michel Marcus_, Nov 20 2013
%Y A066501 Cf. A045309, A066498, A066499, A066500, A066502, A000010.
%K A066501 nonn
%O A066501 1,2
%A A066501 _Benoit Cloitre_, Jan 04 2002
%E A066501 Extended by _Ray Chandler_, Nov 06 2003
%E A066501 Terms 1, 2 and 3 prepended by _Michel Marcus_, Nov 20 2013