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A248879
Numbers k >= 0 such that 2^k*(k+1)!+1 is prime.
1
0, 1, 3, 5, 8, 11, 16, 18, 25, 30, 36, 87, 118, 142, 2789, 3142, 3557, 3686, 4190, 7328
OFFSET
1,3
COMMENTS
a(21) > 10^4.
EXAMPLE
a(3) = 2^3*(3+1)!+1 = 193 which is prime.
MATHEMATICA
Select[Range[0, 10000], PrimeQ[2^#*(#+1)!+1] &]
PROG
(PARI) for(n=0, 10^3, if(ispseudoprime((n+1)!*2^n+1), print1(n, ", "))) \\ Derek Orr, Mar 06 2015
CROSSREFS
Cf. A093154.
Sequence in context: A340318 A175489 A289244 * A014688 A167136 A099836
KEYWORD
nonn,more
AUTHOR
Robert Price, Mar 05 2015
STATUS
approved