Exponent of 7 (value of j) in n-th number of form 2^i*7^j.

Terms

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