OFFSET
1,1
COMMENTS
a(7) = 167! + 2^167 - 1 = 1503616514 ... 959365500927 has 301 digits ;
a(8) = 2609! + 2^2609 - 1 = 4110644622 ... 780469952511 has 7783 digits.
EXAMPLE
for k=3, 13 is in the sequence because 3! + 2^3 - 1 = 13 is prime.
MATHEMATICA
lst={}; Do[ q=k!+2^k-1; If[PrimeQ[q], AppendTo[lst, q]], {k, 0, 400}]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Feb 22 2011
STATUS
approved