OFFSET
1,1
COMMENTS
LINKS
Daniel Starodubtsev, Table of n, a(n) for n = 1..10000
EXAMPLE
2 is in this sequence because (2-1)*2^2+1=5 and 2^2+(2-1)=5 are both prime.
MATHEMATICA
Select[Range[600], PrimeQ[#^2+#-1]&&PrimeQ[#^2(#-1)+1]&] (* Farideh Firoozbakht, Mar 17 2014 *)
PROG
(Magma) k := 1;
for n in [1..10000] do
if IsPrime(k*(n - 1)*n^2 + 1) and IsPrime(k*n^2 + n - 1) then
n;
end if;
end for;
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Lopatin following a suggestion from Juri-Stepan Gerasimov, Mar 15 2014
STATUS
approved