OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..10000
EXAMPLE
57 = 7^2+7+1 (7 is prime) and 57^2+57+1 = 3307 is also prime. Thus, 57 is a member of this sequence.
MAPLE
for k from 1 do
p := ithprime(k) ;
n := numtheory[cyclotomic](3, p) ;
pn := numtheory[cyclotomic](3, n) ;
if isprime( pn) then
print(n) ;
end if;
end do: # R. J. Mathar, Feb 07 2014
MATHEMATICA
Select[Table[p^2+p+1, {p, Prime[Range[500]]}], PrimeQ[#^2+#+1]&] (* Harvey P. Dale, Feb 09 2014 *)
PROG
(Python)
import sympy
from sympy import isprime
{print(n**2+n+1) for n in range(10**4) if isprime(n) and isprime((n**2+n+1)**2+(n**2+n+1)+1)}
(PARI) s=[]; forprime(p=2, 4000, if(isprime(p^4+2*p^3+4*p^2+3*p+3), s=concat(s, p^2+p+1))); s \\ Colin Barker, Feb 07 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Derek Orr, Feb 06 2014
STATUS
approved