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 A277628 #12 Sep 12 2017 15:15:47 %S A277628 1,3,21,936340943,10460353197,9374251222371,23326283250291, %T A277628 615790788171551 %N A277628 Positive integers n such that 3^n == 6 (mod n). %C A277628 No other terms below 10^15. - _Max Alekseyev_, Sep 12 2017 %o A277628 (PARI) isok(n) = Mod(3, n)^n == Mod(6, n); %Y A277628 Solutions to 3^n == k (mod n): A277340 (k=-11), A277289 (k=-7), A277288 (k=-5), A015973 (k=-2), A015949 (k=-1), A067945 (k=1), A276671 (k=2), A276740 (k=5), this sequence (k=6), A277126 (k=7), A277630 (k=8), A277274 (k=11). %K A277628 nonn,more %O A277628 1,2 %A A277628 _Dmitry Ezhov_, Oct 24 2016 %E A277628 a(6)-a(8) from _Max Alekseyev_, Sep 12 2017