A122724 Primes p such that (2p)! - 1 is also prime.

2, 3, 7, 19, 47, 83, 487

Offset: 1

Author

Alexander Adamchuk, Sep 23 2006

Keywords

• hard
• more
• nonn

Comments

Corresponding primes of the form (2p)! - 1 are {23,719,87178291199,523022617466601111760007224100074291199999999,...}.

No other terms < 20663. - Robert Price, Mar 02 2012

No other terms < 104002 using A002982. - Michael S. Branicky, May 14 2025

Crossrefs

Cf. A002982, A103317.

Programs

Mathematica

Select[Prime[Range[100]],PrimeQ[(2#)!-1]&] (* James C. McMahon, Nov 09 2024 *)