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A261714
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Numbers n such that n! + 2^n + 1 is prime.
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2
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OFFSET
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1,2
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COMMENTS
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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
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LINKS
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Table of n, a(n) for n=1..5.
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EXAMPLE
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For n=2, n! + 2^n + 1 = 2! + 2^2 + 1 = 7, which is prime.
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MATHEMATICA
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Select[Range@ 2000, PrimeQ[#! + 2^# + 1] &] (* Michael De Vlieger, Aug 29 2015 *)
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PROG
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(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
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CROSSREFS
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Cf. A007611.
Sequence in context: A270372 A018507 A018523 * A204548 A018532 A270381
Adjacent sequences: A261711 A261712 A261713 * A261715 A261716 A261717
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KEYWORD
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nonn,more,hard
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AUTHOR
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Altug Alkan, Aug 29 2015
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STATUS
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approved
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