a(n) = (2^A000959(n)) - 1.

Terms

a(0) =1a(1) =7a(2) =127a(3) =511a(4) =8191a(5) =32767a(6) =2097151a(7) =33554431a(8) =2147483647a(9) =8589934591a(10) =137438953471