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 A127820 #15 Mar 08 2024 09:01:45
%S A127820 11,5,15,10,7,21,25,34,549,134,120593747,13,20395,26,1713,20,203,57,
%T A127820 49,62,1707,122,55,30,793,118,45,58,1921,38,1853,56,339,110,4223,42,
%U A127820 85,106,1689,52,841,642,4475,70,51,551,11683,147,168061,94,129,623,1243895,90
%N A127820 a(n) = least k such that the remainder when 12^k is divided by k is n.
%H A127820 Robert G. Wilson v, <a href="/A127820/a127820.txt">Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found</a>
%t A127820 t = Table[0, {10000} ]; k = 1; While[ k < 3000000000, a = PowerMod[12, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* _Robert G. Wilson v_, Aug 04 2009 *)
%Y A127820 Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127821.
%K A127820 nonn
%O A127820 1,1
%A A127820 _Alexander Adamchuk_, Jan 30 2007
%E A127820 More terms from _Robert G. Wilson v_, Feb 06 2007