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A077314 Primes of the form 2^r*7^s - 1. 5
3, 7, 13, 31, 97, 127, 223, 1567, 3583, 4801, 6271, 8191, 19207, 25087, 33613, 76831, 131071, 401407, 524287, 917503, 1229311, 1605631, 3764767, 6588343, 14680063, 184473631, 737894527, 2147483647, 2259801991, 2877292543, 3758096383 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In all terms except 3, r is odd. - Robert Israel, Jun 08 2018

LINKS

Robert Israel, Table of n, a(n) for n = 1..1736

MAPLE

N:= 10^30: # for all terms <= N

sort(select(isprime, [3, seq(seq(2^r*7^s-1, r=1..ilog2((N+1)/7^s), 2),

s=0..floor(log[7]((N+1)/2)))])); # Robert Israel, Jun 08 2018

CROSSREFS

Cf. A023509, A077313.

Sequence in context: A247895 A155128 A176589 * A069246 A253850 A087578

Adjacent sequences:  A077311 A077312 A077313 * A077315 A077316 A077317

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Nov 04 2002

EXTENSIONS

Corrected and extended by Ray Chandler, Aug 02 2003

STATUS

approved

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Last modified April 24 22:26 EDT 2019. Contains 322446 sequences. (Running on oeis4.)