Monotonic ordering of nonnegative differences 2^i-7^j, for 40>=i>=0, j>=0.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =9a(5) =15a(6) =25a(7) =31a(8) =57a(9) =63a(10) =79a(11) =121a(12) =127a(13) =169a(14) =207a(15) =249a(16) =255a(17) =463a(18) =505a(19) =511a(20) =681a(21) =975a(22) =1017a(23) =1023a(24) =1695a(25) =1705a(26) =1999a(27) =2041a(28) =2047a(29) =3753