Least k>0 such that (p*2^k-1)/3 is prime, or zero if no k exists, where p=prime(n).

Terms

a(0) =3a(1) =0a(2) =1a(3) =4a(4) =1a(5) =2a(6) =1a(7) =4a(8) =3a(9) =1a(10) =2a(11) =4a(12) =3a(13) =4a(14) =1a(15) =9107a(16) =3a(17) =6a(18) =2a(19) =1a(20) =2a(21) =4a(22) =7a(23) =1a(24) =6a(25) =1a(26) =2a(27) =1a(28) =32a(29) =11