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A215913 Primes of the form 2*!n-1. 0
3, 17, 352429681, 4581585863 (list; graph; refs; listen; history; text; internal format)
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: A225728 A175984 A051710 * A162713 A161473 A208493

Adjacent sequences:  A215910 A215911 A215912 * A215914 A215915 A215916

KEYWORD

nonn

AUTHOR

Michel Lagneau, Aug 26 2012

STATUS

approved

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Last modified June 6 18:59 EDT 2020. Contains 334832 sequences. (Running on oeis4.)