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 A015961 #21 Aug 28 2021 02:50:41 %S A015961 1,13,169,1027,2197,13351,28561,81133,173563,371293,468481,685633, %T A015961 1054729,2256319,2890927,4826809,6090253,6409507,8913229,13711477, %U A015961 29332147,37009999,37582051,54165007,62748517,79173289,83323591,115871977,178249201,228383233 %N A015961 Positive integers k such that k | (12^k + 1). %Y A015961 Solutions to b^k == -1 (mod k): A006521 (b=2), A015949 (b=3), A015950 (b=4), A015951 (b=5), A015953 (b=6), A015954 (b=7), A015955 (b=8), A015957 (b=9), A015958 (b=10), A015960 (b=11), this sequence (b=12), A015963 (b=13), A015965 (b=14), A015968 (b=15), A015969 (b=16). %Y A015961 Column k=12 of A333429. %K A015961 nonn %O A015961 1,2 %A A015961 _Robert G. Wilson v_ %E A015961 More terms from _Max Alekseyev_, Aug 01 2011 %E A015961 a(30) from _Jon E. Schoenfield_, Aug 27 2021