Exponent of 2 in prime factorization of prime(n)*prime(n-1) - 1.

Terms

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