OFFSET
1,1
COMMENTS
For all primes q>3, we have q=6k+-1 for some k, which makes it easy to show that 6 divides q^2+5.
(n^2+5)/6 is an integer for all primes except 2 and 3. - Michael B. Porter, Apr 14 2010
MATHEMATICA
Select[Prime[Range[215]], PrimeQ[(#^2+5)/6]&] (* James C. McMahon, Sep 13 2024 *)
PROG
(PARI) isA118915(n)=if(n^2%6==1, isprime(n)&&isprime((n^2+5)/6), 0) \\ Michael B. Porter, Apr 14 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, May 05 2006
STATUS
approved