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A139455 Numbers n such that primorial(n)/2 + 1024 is prime. 5
3, 4, 5, 7, 11, 14, 15, 22, 30, 32, 37, 53, 83, 123, 156, 212, 215, 314, 331, 417, 555, 930, 3809, 3945, 15738 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(26) > 25000. - Robert Price, Jul 02 2017

LINKS

Table of n, a(n) for n=1..25.

MATHEMATICA

k = 1/2; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 1024], Print[n]; AppendTo[a, n]], {n, 325}]; a

PROG

(PARI) isok(n) = isprime(1024+prod(k=2, n, prime(k))); \\ Michel Marcus, Jul 02 2017

CROSSREFS

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

Sequence in context: A001605 A216570 A101762 * A095880 A076497 A137950

Adjacent sequences:  A139452 A139453 A139454 * A139456 A139457 A139458

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 21 2008

EXTENSIONS

a(18)-a(22) from Ray Chandler, Jun 16 2013

a(23)-a(25) from Robert Price, Jul 02 2017

STATUS

approved

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Last modified December 15 22:36 EST 2018. Contains 318155 sequences. (Running on oeis4.)