Numbers k such that 2^psi(k) == -1 (mod k) where psi(k) = A001615(k).

Terms

a(0) =1a(1) =5a(2) =25a(3) =125a(4) =625a(5) =3125a(6) =4097a(7) =7361a(8) =15625a(9) =69649a(10) =78125a(11) =85073a(12) =125137a(13) =390625a(14) =658529a(15) =987377a(16) =1184033a(17) =1953125a(18) =2127329a(19) =2358529a(20) =3187313a(21) =3999137a(22) =9765625a(23) =11194993a(24) =16777217a(25) =16785409a(26) =20128561a(27) =20502593a(28) =30030769a(29) =36164593