OFFSET
6,1
COMMENTS
A set of primes is a covering set for k*2^m - 1 if for every positive integer m there is some prime in the set which divides k*2^m - 1. Only minimal covering sets are considered here (those which would not remain covering sets with the removal of any element).
LINKS
EXAMPLE
509203 has the covering set {3, 5, 7, 13, 17, 241}.
777149 has the covering set {3, 5, 7, 13, 19, 37, 73}.
7106977 has the covering set {3, 5, 13, 17, 19, 109, 241, 433}.
60014203 has the covering set {3, 5, 7, 11, 13, 31, 41, 61, 151}.
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Arkadiusz Wesolowski, Apr 19 2012
STATUS
approved