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A122719 Primes p such that (2p)!! - 1 is prime. 0

%I

%S 2,3,13,41,59,97,107,421,1663,22159

%N Primes p such that (2p)!! - 1 is prime.

%C a(n) are the primes from A091415[n] = {2,3,4,8,13,32,41,45,59,97,107,364,421,...} Numbers n such that n!*2^n - 1 is prime. Corresponding primes of the form (2p)!! - 1 are {3,5,270269,26226140915375977206881249, 58431212742946338570036120182498518593749,...}

%C No other terms up to 3000. - _Stefan Steinerberger_, Sep 09 2007

%t Select[Prime[Range[651]],PrimeQ[(2#)!!-1]&]

%Y Cf. A007749, A117141, A091415.

%K hard,more,nonn

%O 1,1

%A _Alexander Adamchuk_, Sep 23 2006

%E a(9) from _Stefan Steinerberger_, Sep 09 2007

%E a(10) from _Robert Price_, Nov 26 2013

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Last modified October 15 07:56 EDT 2019. Contains 328026 sequences. (Running on oeis4.)