The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A206430 Least k such that k*2^m - 1 has a covering set with precisely n primes. 1
 509203, 777149, 7106977, 60014203 (list; graph; refs; listen; history; text; internal format)
 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 Table of n, a(n) for n=6..9. Wikipedia, Covering set Wikipedia, Riesel number 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 Cf. A076337, A101036. Sequence in context: A258154 A101036 A244070 * A182296 A263958 A273987 Adjacent sequences: A206427 A206428 A206429 * A206431 A206432 A206433 KEYWORD more,nonn AUTHOR Arkadiusz Wesolowski, Apr 19 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 13 03:33 EDT 2024. Contains 375857 sequences. (Running on oeis4.)