OFFSET
1,1
COMMENTS
If n is a multiple of 4 then 4 + m^n is prime iff m = 1.
4 + m^(4*x) = (m^(2*x)-2*m^x+2) * (m^(2*x)+2*m^x+2). - Jens Kruse Andersen, Sep 02 2014
LINKS
Zak Seidov and Jens Kruse Andersen, Table of n, a(n) for n = 1..1000 (first 200 terms from Zak Seidov)
PROG
(PARI)
a(n)=if(n%4==0, return(1)); m=2; while(!ispseudoprime(4+m^n), m++); return(m)
vector(100, n, a(n)) \\ Derek Orr, Aug 29 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Aug 29 2014
STATUS
approved