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A258616 Numbers n such that n!!-16 is prime. 7
7, 9, 13, 17, 25, 185, 197, 261, 407, 593, 1535, 2129, 2139, 2581, 4133, 4665, 15787, 25337, 27449 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding primes are 89, 929, 135119, 34459409, ... .

a(20) > 50000.

LINKS

Table of n, a(n) for n=1..19.

Joe McLean, Interesting Sources of Probable Primes

MATHEMATICA

Select[Range[4, 1000], PrimeQ[#!!-16]&] (* Robert Price, Jun 05 2015 *)

Do[f=n!! - 16; If[PrimeQ[f], Print[{n, f}]], {n, 4, 600}] (* Vincenzo Librandi, Jun 06 2015 *) (see comment)

CROSSREFS

Cf. A006882, A007749, A094144, A123910.

Sequence in context: A329166 A222945 A129069 * A125866 A027692 A343001

Adjacent sequences:  A258613 A258614 A258615 * A258617 A258618 A258619

KEYWORD

hard,more,nonn

AUTHOR

Robert Price, Jun 05 2015

STATUS

approved

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Last modified January 22 18:37 EST 2022. Contains 350488 sequences. (Running on oeis4.)