Interlaces A007583 with A083420.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =11a(5) =31a(6) =43a(7) =127a(8) =171a(9) =511a(10) =683a(11) =2047a(12) =2731a(13) =8191a(14) =10923a(15) =32767a(16) =43691a(17) =131071a(18) =174763a(19) =524287a(20) =699051a(21) =2097151a(22) =2796203a(23) =8388607a(24) =11184811a(25) =33554431a(26) =44739243a(27) =134217727a(28) =178956971a(29) =536870911