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 A056217 #12 Dec 08 2017 11:26:23
%S A056217 37,613,733,1597,2677,3037,4957,5197,5641,7129,7333,7573,8521,8677,
%T A056217 11317,14281,14293,15289,15373,16249,17053,17293,17317,19441,20161,
%U A056217 21397,21613,21997,23053,23197,24133,25357,25717,26053,26293,27277
%N A056217 Primes p for which the period of reciprocal 1/p is (p-1)/12.
%C A056217 Cyclic numbers of the twelfth degree (or twelfth order): the reciprocals of these numbers belong to one of twelve different cycles. Each cycle has the (number minus 1)/12 digits.
%C A056217 Primes p such that the order of 2 mod p is (p-1)/12. - _Robert Israel_, Dec 08 2017
%H A056217 Robert Israel, <a href="/A056217/b056217.txt">Table of n, a(n) for n = 1..10000</a>
%H A056217 <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a>
%p A056217 select(p -> isprime(p) and numtheory:-order(10, p) = (p-1)/12, [seq(i,i=13..30000,12)]); # _Robert Israel_, Dec 08 2017
%t A056217 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, 3000]], f[ # ] == 12 &]
%K A056217 nonn,base
%O A056217 1,1
%A A056217 _Robert G. Wilson v_, Aug 02 2000