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 A056216 #16 Jun 29 2021 05:55:50
%S A056216 353,3499,10429,13619,15269,20219,20593,23057,23189,24091,25741,30713,
%T A056216 35509,38567,45233,49171,57179,57223,60149,63691,63977,67783,77023,
%U A056216 85229,88463,90619,91367,93941,96779,108967,109913,110221,112069
%N A056216 Primes p whose period of reciprocal equals (p-1)/11.
%C A056216 Cyclic numbers of the eleventh degree (or eleventh order): the reciprocals of these numbers belong to one of eleven different cycles. Each cycle has the (number minus 1)/11 digits.
%H A056216 Amiram Eldar, <a href="/A056216/b056216.txt">Table of n, a(n) for n = 1..10000</a>
%H A056216 <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a>
%t A056216 f[n_Integer] := Block[{ds = Divisors[n - 1]}, (n - 1)/Take[ ds, Position[ PowerMod[ 10, ds, n], 1] [[1, 1]]] [[ -1]]]; Select[ Prime[ Range[4, 11000]], f[ # ] == 11 &]
%Y A056216 Cf. A097443, A055628, A056157, A056210, A056211, A056212, A056213, A056214, A056215, A056217, A098680, A135073.
%K A056216 nonn,base
%O A056216 1,1
%A A056216 _Robert G. Wilson v_, Aug 02 2000
%E A056216 Edited by _N. J. A. Sloane_, Apr 30 2007