OFFSET
1,2
COMMENTS
These Repunit numbers of the form (10^n-1)/9 have no prime factors congruent to 3 (mod 7) or 5 (mod 7) or 6 (mod 7) to an odd power. Also the power of 2 is not 1.
LINKS
Samuel S. Wagstaff, Jr. The Cunningham Project
CROSSREFS
KEYWORD
nonn
AUTHOR
V. Raman, Sep 08 2012
STATUS
approved