[Harvey Dubner: New Repunit R(109297)]

[Olivier Gérard]

 From the Number Theory List,

Harvey Dubner wrote:

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          New Probable Prime Repunit, R(109297)

On March 28 I found a new probable prime repunit, R(109297), which
consists of 109297 1's. It is effectively impossible to prove true
primality at this time.

 The only known repunit primes are R(2), R(19), R(23), R(317), and
 R(1031). In 1999 I found the PRP repunit R(49081), and in 2000 Lew
 Baxter found the PRP repunit R(86453).

I plan to try to raise the test limit to 200000. My continued interest
in repunits is due primarily to the fact that my first project on a
home computer (1980) was searching for repunit primes.

References:

H.C, Williams and H. Dubner, The Primality of R1031,
Math. Comp. 47(176), Oct 1986, 703-711.

Harvey Dubner, Repunit R49081 is a Probable Prime,
Math. Comp. 71(238), (2002), 833-835.

A004023, On-line Encyclopedea of Integer Sequences.    

Harvey Dubner