Numbers k such that 12^k == -1 (mod k-1).

Terms

a(0) =2a(1) =6a(2) =30a(3) =146a(4) =42486a(5) =102966a(6) =597198a(7) =2847366a(8) =7998606a(9) =13133666a(10) =30478158a(11) =67622310a(12) =74476206a(13) =101258190a(14) =105161166a(15) =106364286a(16) =187605438a(17) =230000550a(18) =242915166a(19) =401913582a(20) =406756350a(21) =444314574a(22) =848205078a(23) =899715894a(24) =1508418054a(25) =1575220350a(26) =1578086334a(27) =1691859102