Numbers that are not the sum of two evil numbers.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =31a(5) =127a(6) =511a(7) =2047a(8) =8191a(9) =32767a(10) =131071a(11) =524287a(12) =2097151a(13) =8388607a(14) =33554431a(15) =134217727a(16) =536870911a(17) =2147483647a(18) =8589934591a(19) =34359738367a(20) =137438953471a(21) =549755813887