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 A055694 #9 Jul 11 2021 13:08:51
%S A055694 2,3,5,7,13,62,75,378,637,2295,10933,24255,31125,50787,53685,55575,
%T A055694 176565,193242,243165,290675,415215,579397,728035,728742,741015,
%U A055694 760410,1281423,1447515,1664205,1975974,4020030,4794075,5778525,7189014
%N A055694 Numbers k such that 11^k == -1 (mod k-1).
%t A055694 Do[If[PowerMod[11, n, n-1]==n-2, Print[n]], {n, 2, 10^7}]
%K A055694 nonn
%O A055694 1,1
%A A055694 _Robert G. Wilson v_, Jun 09 2000