OFFSET
1,1
COMMENTS
Terms greater than 1000 often correspond only to strong pseudoprimes. [Clarified by M. F. Hasler, Sep 15 2013]
All terms are prime. - Robert Price, Jan 20 2013
a(12) > 10^5. - Robert Price, Jan 20 2013
To elaborate on Robert Price's comment that all terms are prime: This is also true for all other sequences of numbers n such that k^n - (k-1)^n is prime. It is easy to prove by elementary means that if n = a * b, then k^n - (k-1)^n is divisible by k^(n-a) - (k-1)^(n-a) and k^(n-b) - (k-1)^(n-b). - Alonso del Arte, Sep 15 2013
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Mike Oakes, May 18 2001, May 19 2001
EXTENSIONS
a(8)-a(11) from Robert Price, Jan 20 2013
STATUS
approved