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

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

Offset

1,1

Comments

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

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

Links

Table of n, a(n) for n=1..7.

Mathematica

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

Crossrefs

Cf. A002982, A103317.

Sequence in context: A069051 A229290 A246033 * A256758 A033844 A037028

Adjacent sequences: A122721 A122722 A122723 * A122725 A122726 A122727

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Sep 23 2006

Status

approved