Numbers k such that 2^(k-1) == 1 + b*k (mod k^2), where b divides k-1.

Terms

a(0) =3a(1) =7a(2) =11a(3) =13a(4) =19a(5) =29a(6) =31a(7) =37a(8) =71a(9) =127a(10) =379a(11) =491a(12) =2047a(13) =2633a(14) =2659a(15) =3373a(16) =8191a(17) =13249a(18) =26893a(19) =70687a(20) =74597a(21) =87211a(22) =131071a(23) =184511a(24) =524287a(25) =642581a(26) =1897121a(27) =2676301a(28) =2703739a(29) =8388607