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A099422 Numbers n such that 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. +0
1
0, 1, 2, 3, 5, 8, 9, 15, 51, 71, 77, 224, 296, 315, 2090, 2906, 3395, 3882, 5114, 6056, 7254, 7995 (list; graph; listen)
OFFSET

1,3

COMMENT

Also numbers n such that (8*10^n-53)/9 is prime.

LINKS

Index entries for primes involving repunits

Makoto Kamada, Factorizations of 88...883.

FORMULA

Equals A056694 + 1 - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

MATHEMATICA

Do[ If[ PrimeQ[ 8(10^n - 1)/9 - 5], Print[n]], {n, 0, 5000}]

CROSSREFS

Sequence in context: A141399 A104737 A120057 this_sequence A056903 A028770 A028800

Adjacent sequences: A099419 A099420 A099421 this_sequence A099423 A099424 A099425

KEYWORD

nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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