OFFSET
1,1
COMMENTS
All k are multiples of 6, k=6j, where j are numbers in A138218.
MATHEMATICA
Select[5*Range[600]^2+1, PrimeQ] (* Harvey P. Dale, Dec 06 2015 *)
PROG
(Magma)[a: n in [0..1000]|IsPrime(a) where a is 1+5*n^2] // Vincenzo Librandi, Dec 13 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Apr 27 2008
STATUS
approved