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A084406 Numbers k such that k#*2^k-1 is prime, where k# = product of primes <= k. 1
2, 3, 7, 8, 14, 16, 18, 20, 40, 42, 44, 53, 134, 154, 185, 187, 191, 197, 200, 201, 230, 235, 239, 244, 256, 282, 303, 358, 489, 536, 665, 684, 719, 1098, 1204, 1400, 1516, 1629, 1903, 1997, 1999, 2104, 2477, 3075, 3676, 3785, 4115, 5429, 5808, 6069, 6276, 9095 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The values corresponding to terms 1098 through 1516 have been proved to be prime.

No more terms < 10000. - L. Joris Perrenet, Mar 18 2020

LINKS

Table of n, a(n) for n=1..52.

The OpenPFGW Project, Primality Tester.

MATHEMATICA

p = 1; Do[If[PrimeQ[n], p *= n]; If[PrimeQ[p*2^n - 1], Print[n]], {n, 2, 10000}] (* Ryan Propper, Sep 05 2005 *)

CROSSREFS

Cf. A034386.

Sequence in context: A105601 A199971 A033082 * A075648 A071527 A307328

Adjacent sequences:  A084403 A084404 A084405 * A084407 A084408 A084409

KEYWORD

nonn

AUTHOR

Jason Earls, Jun 24 2003

EXTENSIONS

More terms from Ryan Propper, Sep 05 2005

a(52) from L. Joris Perrenet, Mar 18 2020

STATUS

approved

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Last modified December 3 18:19 EST 2021. Contains 349467 sequences. (Running on oeis4.)