OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5000
MATHEMATICA
p = 10; a = {}; Do[k = p x^2 - 1; If[PrimeQ[k], AppendTo[a, k]], {x, 1, 1000}]; a
Select[Table[10n^2-1, {n, 1, 800}], PrimeQ] (* Vincenzo Librandi, Dec 07 2011 *)
PROG
(Magma) [a: n in [1..400] | IsPrime(a) where a is 10*n^2-1]; // Vincenzo Librandi, Dec 07 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Sep 02 2008
STATUS
approved