Numbers k such that 2^sigma(k) - k is a prime.

Terms

a(0) =3a(1) =5a(2) =17a(3) =49a(4) =53a(5) =185a(6) =503a(7) =1301a(8) =1689a(9) =1797a(10) =5929a(11) =14747a(12) =20433a(13) =29903a(14) =42137a(15) =64763