A161864 Numbers n such that n^2 + n + 5 and n^2 + n - 5 are both prime.

3, 6, 11, 18, 21, 23, 27, 32, 42, 48, 51, 83, 86, 93, 116, 153, 158, 182, 188, 216, 282, 291, 317, 333, 396, 482, 681, 737, 786, 798, 818, 821, 872, 923, 956, 966, 977, 986, 1007, 1026, 1077, 1082, 1106, 1161, 1287, 1292, 1302, 1337, 1341, 1451, 1467, 1563

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(1)=3 as 12+-5 are primes. a(2)=6 as 42+-5 are primes.

Maple

select(n -> isprime(n^2+n+5) and isprime(n^2+n-5), [$1..2000]); # Robert Israel, Nov 26 2017

Mathematica

q=5; lst5={}; Do[p=n^2+n; If[PrimeQ[p-q]&&PrimeQ[p+q], AppendTo[lst5, n]], {n, 0, 7!}]; lst5

Crossrefs

Cf. A088485, A161863.

Sequence in context: A013932 A302550 A310117 * A351066 A310118 A010335

Adjacent sequences: A161861 A161862 A161863 * A161865 A161866 A161867

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, Jun 20 2009

Extensions

Definition rephrased by R. J. Mathar, Jun 23 2009

Status

approved