Numbers whose base-2 representation is a "nested" palindrome.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =15a(5) =21a(6) =31a(7) =45a(8) =63a(9) =73a(10) =127a(11) =153a(12) =255a(13) =273a(14) =341a(15) =443a(16) =511a(17) =561a(18) =693a(19) =891a(20) =1023a(21) =1057a(22) =1453a(23) =1651a(24) =2047a(25) =2145a(26) =2925a(27) =3315a(28) =4095a(29) =4161