OFFSET
1,1
COMMENTS
No further terms up to 5 million. - Harvey P. Dale, Mar 20 2016
The definition implies 2^(k-1) == 1 (mod k), so all terms are either primes or Sarrus numbers (A001567). There are no further prime terms below 10^12, and no further Sarrus terms below 2^64. - Lucas A. Brown, Feb 19 2024
LINKS
Jan Feitsma, The pseudoprimes below 2^64.
MATHEMATICA
Select[Range[3000], PowerMod[2, #-1, #]==1&&PowerMod[2, #-1, #^2]-1==2*#&] (* Harvey P. Dale, Mar 20 2016 *)
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Alzhekeyev Ascar M, Sep 30 2010
STATUS
approved