Numbers k such that 7^k == -1 (mod k-1).

Terms

a(0) =2a(1) =3a(2) =5a(3) =6a(4) =9a(5) =26a(6) =45a(7) =66a(8) =87a(9) =345a(10) =765a(11) =906a(12) =3926a(13) =8405a(14) =11766a(15) =23805a(16) =35145a(17) =42966a(18) =59685a(19) =95289a(20) =317250a(21) =413325a(22) =416757a(23) =722745a(24) =770066a(25) =890825a(26) =938457a(27) =1325826a(28) =1921986a(29) =3315378