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 A116629 #26 Aug 04 2025 02:38:52
%S A116629 1,2,5,166,287603,9241538,2366680105,8347156585,21682897793,
%T A116629 6988245760865,9045859950329,10076294257985,50299408064905,
%U A116629 254874726648713
%N A116629 Positive integers k such that 13^k == 3 (mod k).
%C A116629 No other terms below 10^15. - _Max Alekseyev_, Nov 24 2017
%C A116629 Some larger terms: 1440926367749746685, 76025040962646716305439353859479569558065. - _Max Alekseyev_, Jun 29 2011
%t A116629 Join[{1, 2}, Select[Range[1, 5000], Mod[13^#, #] == 3 &]] (* _G. C. Greubel_, Nov 19 2017 *)
%t A116629 Join[{1, 2}, Select[Range[10000000], PowerMod[13, #, #] == 3 &]] (* _Robert Price_, Apr 10 2020 *)
%o A116629 (PARI) isok(n) = Mod(13, n)^n == 3; \\ _Michel Marcus_, Nov 19 2017
%Y A116629 Cf. A116609, A050259, A122780, A130422, A123061, A277554.
%Y A116629 Solutions to 13^n == k (mod n): A001022 (k=0), A015963 (k=-1), A116621 (k=1), A116622 (k=2), this sequence (k=3), A116630 (k=4), A116611 (k=5), A116631 (k=6), A116632 (k=7), A295532 (k=8), A116636 (k=9), A116620 (k=10), A116638 (k=11), A116639 (k=15).
%K A116629 nonn,more
%O A116629 1,2
%A A116629 _Zak Seidov_, Feb 19 2006
%E A116629 Two more terms from _Ryan Propper_, Jan 09 2008
%E A116629 Terms 1,2 are prepended and a(9)-a(14) are added by _Max Alekseyev_, Jun 29 2011; Nov 24 2017