OFFSET
1,2
COMMENTS
Inspired by A007611.
First three prime numbers of the form n! + 2^n +1 with positive n value are 7, 41, 40577.
a(5) > 30000. - Giovanni Resta, Aug 30 2015
EXAMPLE
For n=2, n! + 2^n + 1 = 2! + 2^2 + 1 = 7, which is prime.
MATHEMATICA
Select[Range@ 2000, PrimeQ[#! + 2^# + 1] &] (* Michael De Vlieger, Aug 29 2015 *)
PROG
(PARI) for(n=1, 1e3, if(isprime(k=(n!+2^n+1)), print1(n", ")))
(Magma) [n: n in [1..300] | IsPrime(Factorial(n)+2^n+1)]; // Vincenzo Librandi, Aug 30 2015
(PFGW) ABC2 $a! + 2^$a + 1
a: from 0 to 30000
Charles R Greathouse IV, Sep 08 2015
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Altug Alkan, Aug 29 2015
STATUS
approved