Exponent of 2 in prime factorization of prime(n) - 3.

Terms

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