OFFSET
2,1
COMMENTS
Some values with base b=2^x+1 for integers x have also been calculated - see the links.
LINKS
G. Jaeschke, On the smallest k such that all k * 2^n +1 are composite, Math. Comp., 40:181 (1983) 381-384. MR 84k:10006.
Primeform Group, base=2^x+1.
Primeform Group, base=3.
Primeform Group, base=5.
Carlos Rivera, Problem 36. The Liskovets-Gallot numbers, The Prime Puzzles and Problems Connection.
Guido Smetrijns, Andrew J. Walker, Shane Findley, Jim Fougeron, Mikael Klasson, Robert Smith and others, Riesel/Sierpinski in base 3, digest of 43 messages in primeform Yahoo group, May 24, 2004 - Jan 7, 2007. [Cached copy]
Robert Smith, David Broadhurst, Shane Findley, Sierpinski / Riesel base 2^x+1, digest of 4 messages in primeform Yahoo group, Sep 26 - Sep 27, 2004. [Cached copy]
Robert Smith, Guido Smetrijns, Mikael Klasson, Riesel Sierpinski in base 5, digest of 6 messages in primeform Yahoo group, Sep 17 - Sep 18, 2004
EXAMPLE
For base=3, S+1 should be coprime to 3-1 = 2, so S must be even. Find a covering set of multiplicative orders of primes base b and discover S by trial and error using the Chinese Remainder Theorem.
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Smith (robert_smith44(AT)hotmail.com), Oct 02 2006
EXTENSIONS
a(6) from Arkadiusz Wesolowski, Nov 20 2014
a(3) corrected and a(7)-a(45) from Eric Chen, Dec 16 2014
STATUS
approved