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A139442 Numbers n such that primorial(n)/2 - 8 is prime. 5
3, 4, 7, 9, 10, 11, 13, 15, 22, 23, 29, 45, 51, 52, 55, 69, 98, 122, 157, 268, 367, 476, 481, 1670, 1964, 2736, 4696, 7933, 22245 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(30) > 25000. - Robert Price, Jan 13 2017

LINKS

Table of n, a(n) for n=1..29.

MATHEMATICA

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 8] && k > 8, Print[n]; AppendTo[a, n]], {n, 2, 481}]; a

PROG

(PARI) is(n)=ispseudoprime(prod(i=2, n, prime(i))-8) \\ Charles R Greathouse IV, Jun 13 2013

CROSSREFS

Cf. A067026, A067027, A139439-A139457, A103514.

Sequence in context: A010398 A010435 A057709 * A037988 A213508 A088958

Adjacent sequences:  A139439 A139440 A139441 * A139443 A139444 A139445

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 21 2008

EXTENSIONS

a(24)-a(25) from Charles R Greathouse IV, Jun 13 2013

a(26)-a(27) from Ray Chandler, Jun 16 2013

a(28)-a(29) from Robert Price, Jan 13 2017

STATUS

approved

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Last modified March 29 15:16 EDT 2020. Contains 333107 sequences. (Running on oeis4.)