OFFSET
1,1
COMMENTS
Generalized Fermat numbers of the form b^(2^n) + k with k = 2 here.
For b = 2760681, b^(2^n) + 2 is prime for n from 0 to 5
PROG
(PARI) k=2; forstep(b=1, 5*10^7, [4, 2, 2, 2], i=0; for(n=0, 4, m=b^2^n+k; if(isprime(m), i++; if(i>4, print([b, m, n, i])))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Robin Garcia, May 06 2013
EXTENSIONS
a(10)-a(25) from Giovanni Resta, May 06 2013
STATUS
approved