A139291 a(n) = 2^(2*prime(n) - 3) - 1.

1, 7, 127, 2047, 524287, 8388607, 2147483647, 34359738367, 8796093022207, 36028797018963967, 576460752303423487, 2361183241434822606847, 604462909807314587353087, 9671406556917033397649407, 2475880078570760549798248447, 10141204801825835211973625643007

Offset: 1

Author

Omar E. Pol, Apr 13 2008

Keywords

• nonn

Crossrefs

Cf. A139286, A139287, A139288, A139289, A139290, A139293, A139294, A139306.

Programs

Mathematica

(2^(2#-1))/4-1&/@Prime[Range[20]] (* Harvey P. Dale, May 08 2011 *)

Formula

a(n) = A139286(n)/4 - 1.

a(n) = A000225(A131426(n)). - Max Alekseyev, Mar 07 2020

a(n) = A139290(n) - 1. - Omar E. Pol, Mar 10 2020

Extensions

Edited by Max Alekseyev, May 03 2009, Mar 07 2020