A267378 Primes of the form k^4 - k^2 + 7.

7, 19, 79, 607, 9907, 20599, 65287, 104659, 129967, 331207, 1047559, 1184839, 1872799, 3746167, 4098607, 6762607, 7308919, 11313139, 20146639, 21376759, 28392919, 43040167, 54693427, 59961799, 84925447, 104050207, 108232819, 131068159, 168883027, 187375039

Offset: 1

Author

Emre APARI, Jan 13 2016

Keywords

• nonn
• easy

Comments

From Robert Israel, Jan 18 2016: (Start)

Subset of A005471.

All terms == 7 or 19 (mod 30). (End)

Examples

			k = 5: 5^4-5^2+7=607 (is prime).
		

Crossrefs

Cf. A005471.

Programs

Magma

[a: n in [1..150] | IsPrime(a) where a is n^4-n^2+7]; // Vincenzo Librandi, Jan 15 2016

Maple

select(isprime, [seq(x^4-x^2+7,x=1..1000)]); # Robert Israel, Jan 18 2016

Mathematica

Select[Table[k^4 - k^2 + 7, {k, 100}], PrimeQ] (* Michael De Vlieger, Jan 13 2016 *)

PARI

lista(nn) = for(n=1, nn, if(ispseudoprime(p=n^4-n^2+7), print1(p, ", "))); \\ Altug Alkan, Jan 15 2016

Extensions

More terms from Vincenzo Librandi, Jan 15 2016