Numbers k=3*m+1 such that 2^m == 1 (mod k).

Terms

a(0) =1a(1) =31a(2) =43a(3) =109a(4) =127a(5) =157a(6) =223a(7) =229a(8) =277a(9) =283a(10) =307a(11) =397a(12) =433a(13) =439a(14) =457a(15) =499a(16) =601a(17) =643a(18) =691a(19) =727a(20) =733a(21) =739a(22) =811a(23) =919a(24) =997a(25) =1021a(26) =1051a(27) =1069a(28) =1093a(29) =1327