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 A015960 #21 Nov 09 2022 12:16:22 %S A015960 1,2,3,9,27,81,111,122,243,333,729,999,2187,2997,4107,6561,7442,8991, %T A015960 10233,12321,13203,19683,24753,26973,30699,36963,39609,59049,74259, %U A015960 80919,89426,92097,110889,118341,118827,151959,177147,222777 %N A015960 Numbers k such that k | 11^k + 1. %H A015960 Seiichi Manyama, <a href="/A015960/b015960.txt">Table of n, a(n) for n = 1..200</a> %t A015960 Select[Range[250000],PowerMod[11,#,#]==#-1&] (* _Harvey P. Dale_, Nov 09 2022 *) %Y A015960 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), this sequence (b=11), A015961 (b=12), A015963 (b=13), A015965 (b=14), A015968 (b=15), A015969 (b=16). %Y A015960 Cf. A333134. %Y A015960 Column k=11 of A333429. %K A015960 nonn %O A015960 1,2 %A A015960 _Robert G. Wilson v_