OFFSET
2,2
COMMENTS
Are there any negative terms?
Of course the Goldbach conjecture implies that the answer is "no"; further, the first thousand terms are positive. - Charles R Greathouse IV, Mar 16 2016
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 2..386
FORMULA
a(n) = A047949(n^n). - Michel Marcus, Jun 09 2013
EXAMPLE
a(4) = 253 since 4^4-253 = 3 and 4^4+253 = 509 are both prime.
PROG
(PARI) a(n)=my(N=n^n); forprime(p=2, N, if(isprime(2*N-p), return(N-p))); -1 \\ Charles R Greathouse IV, Mar 16 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Lior Manor, Sep 18 2002
STATUS
approved