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A096547 Primes p such that primorial(p)/2 - 2 is prime. 5
5, 7, 11, 13, 17, 19, 23, 31, 41, 53, 71, 103, 167, 431, 563, 673, 727, 829, 1801, 2699, 4481, 6121, 7283, 9413, 10321, 12491, 17807, 30307 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

a(3)=7 because primorial(7)/2 - 2 = A070826(4) - 2 = 2*3*5*7/2 - 2 = 103 is prime.

MATHEMATICA

k = 1; Do[k *= Prime[n]; If[PrimeQ[k - 2], Print[Prime[n]]], {n, 2, 3276}] (* Ryan Propper, Oct 25 2005 *&)

CROSSREFS

Cf. A070826, A096177 primes p such that primorial(p)/2+2 is prime, A096178 primes of the form primorial(p)/2+2, A014545 primorial primes, A087398.

Sequence in context: A230227 A101635 A118941 * A216524 A128824 A098420

Adjacent sequences:  A096544 A096545 A096546 * A096548 A096549 A096550

KEYWORD

nonn,more,hard

AUTHOR

Hugo Pfoertner, Jun 27 2004

EXTENSIONS

5 more terms from Ryan Propper, Oct 25 2005

STATUS

approved

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Last modified July 29 09:31 EDT 2021. Contains 346344 sequences. (Running on oeis4.)