OFFSET
1,1
LINKS
Daniel Starodubtsev, Table of n, a(n) for n = 1..10000
EXAMPLE
6 is this sequence because (6-1)*6^2-1 = 179, (6-1)*6^2+1 = 181, 6^2-6+1 = 31 and 6^2+6-1 = 41 are all primes.
PROG
(Magma) k := 1;
for n in [1..100000] do
if IsPrime(k*(n - 1)*n^2 + 1) and IsPrime(k*(n - 1)*n^2 - 1) and IsPrime(k*n^2 + n - 1) and IsPrime(k*n^2 - n + 1) then
n;
end if;
end for;
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ilya Lopatin and Juri-Stepan Gerasimov, Mar 16 2014
EXTENSIONS
Edited by Alois P. Heinz, Mar 19 2014
STATUS
approved