OFFSET
1,1
MATHEMATICA
p = 10; a = {}; Do[k = p x^2 - 1; If[PrimeQ[k], AppendTo[a, x]], {x, 1, 1000}]; a
Select[Range[500], PrimeQ[10#^2-1]&] (* Harvey P. Dale, Nov 11 2020 *)
PROG
(PARI) is(n)=isprime(10*n^2-1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Sep 02 2008
STATUS
approved