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 A128124 #26 Jun 13 2021 03:22:48 %S A128124 1,2,4,5,3763,125714,167716,1803962,2895548,4031785,36226466, %T A128124 16207566916,103742264732,29000474325364,51053256144532, %U A128124 219291270961199,1611547934753332,5816826177630619 %N A128124 Numbers k such that 2^k == 12 (mod k). %H A128124 Joe K. Crump, <a href="http://web.archive.org/web/20120104074313/http://www.immortaltheory.com/NumberTheory/2nmodn.htm">2^n mod n</a> %H A128124 OEIS Wiki, <a href="/wiki/2^n mod n">2^n mod n</a> %t A128124 m = 12; Join[Select[Range[m], Divisible[2^# - m, #] &], %t A128124 Select[Range[m + 1, 10^6], PowerMod[2, #, #] == m &]] (* _Robert Price_, Oct 08 2018 *) %Y A128124 Cf. A015910, A036236, A050259, A033981, A051447, A033982, A051446, A033983, A128121, A128122, A128123, A128125, A128126. %K A128124 hard,more,nonn %O A128124 1,2 %A A128124 _Alexander Adamchuk_, Feb 15 2007 %E A128124 More terms from _Ryan Propper_, Mar 23 2007 %E A128124 1, 2, 4 and 5 added by _N. J. A. Sloane_, Apr 23 2007 %E A128124 a(13)-a(15) from _Max Alekseyev_, May 19 2011 %E A128124 a(15) corrected, a(16)-a(18) added by _Max Alekseyev_, Oct 02 2016