OFFSET
0,1
COMMENTS
!n is a subfactorial number (A000166). The corresponding n are {3, 4, 12, 13, 97,...}.
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
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 26 2012
STATUS
approved