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 A261714 Numbers n such that n! + 2^n + 1 is prime. 2
 0, 2, 4, 8, 72 (list; graph; refs; listen; history; text; internal format)
 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 LINKS Table of n, a(n) for n=1..5. 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 Cf. A007611. Sequence in context: A270372 A018507 A018523 * A204548 A018532 A270381 Adjacent sequences: A261711 A261712 A261713 * A261715 A261716 A261717 KEYWORD nonn,more,hard AUTHOR Altug Alkan, Aug 29 2015 STATUS approved

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Last modified August 10 22:33 EDT 2024. Contains 375058 sequences. (Running on oeis4.)