Number of odd semiprimes between 2^(n-1) and 2^n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =2a(6) =7a(7) =13a(8) =27a(9) =52a(10) =104a(11) =210a(12) =398a(13) =807a(14) =1542a(15) =3046a(16) =5936a(17) =11565a(18) =22584a(19) =44012a(20) =86062a(21) =167786a(22) =327936a(23) =640630a(24) =1252327a(25) =2448518a(26) =4791344a(27) =9378159a(28) =18364095a(29) =35979682