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A262772
Numbers n such that n!! - 32 is prime.
5
7, 45, 67, 145, 411, 825, 1021, 4039, 9069, 9789, 12463, 15137, 26313, 27499
OFFSET
1,1
COMMENTS
Corresponding primes are 73, 25373791335626257947657609343, ... .
a(15) > 50000.
MATHEMATICA
Select[Range[0, 50000], If[#!! - 32 > 0, PrimeQ[#!! - 32]] &]
PROG
(Magma) DoubleFactorial:=func< n | &*[n..2 by -2] >; [ n: n in [7..450] | IsPrime(DoubleFactorial(n) -32) ]; // Vincenzo Librandi, Oct 01 2015
(PARI) for(n=1, 1e4, if (isprime(prod(k=0, (n-1)\2, n - 2*k ) - 32), print1(n", "))) \\ Altug Alkan, Oct 01 2015
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Robert Price, Sep 30 2015
STATUS
approved