OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Range[200], !PrimeQ[2Prime[#]^2 - 1]&]
PROG
(Magma) [n: n in [1..220]| not IsPrime(2*NthPrime(n)^2-1)];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 18 2013
STATUS
approved