A215913 Primes of the form 2*!n-1.

3, 17, 352429681, 4581585863

Offset

0,1

Comments

!n is a subfactorial number (A000166). The corresponding n are {3, 4, 12, 13, 97,...}.

Links

Table of n, a(n) for n=0..3.

Example

The prime 17 =  2* !4 - 1 = 2*9 -1 is in the sequence.

Maple

with(numtheory): f:=n->sum(n!*(((-1)^k)*1/k!), k=0..n):for n from 1 to 150 do: if type(2*f(n)-1, prime) = true then printf(`%d, `, 2*f(n)-1):else fi:od:

Mathematica

a={}; Do[p= 2* Subfactorial[n]-1; If[PrimeQ[p], AppendTo[a, p]], {n, 0, 800}]; Print[a];

Crossrefs

Cf. A006882, A215912.

Sequence in context: A351590 A175984 A051710 * A162713 A161473 A208493

Adjacent sequences: A215910 A215911 A215912 * A215914 A215915 A215916

Keyword

nonn

Author

Michel Lagneau, Aug 26 2012

Status

approved