As a binary numeral, the bit 2^(m-1) of a(n) is 1 iff m is a proper divisor of n.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =1a(5) =7a(6) =1a(7) =11a(8) =5a(9) =19a(10) =1a(11) =47a(12) =1a(13) =67a(14) =21a(15) =139a(16) =1a(17) =295a(18) =1a(19) =539a(20) =69a(21) =1027a(22) =1a(23) =2223a(24) =17a(25) =4099a(26) =261a(27) =8267a(28) =1a(29) =16951