Smallest m >= 0 such that n*2^m + 1 is prime, or -1 if no such m exists.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =1a(5) =0a(6) =2a(7) =1a(8) =1a(9) =0a(10) =1a(11) =0a(12) =2a(13) =1a(14) =1a(15) =0a(16) =3a(17) =0a(18) =6a(19) =1a(20) =1a(21) =0a(22) =1a(23) =2a(24) =2a(25) =1a(26) =2a(27) =0a(28) =1a(29) =0