

A161864


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


2



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
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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+n5), [$1..2000]); # Robert Israel, Nov 26 2017


MATHEMATICA

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


CROSSREFS

Cf. A088485, A161863.
Sequence in context: A013932 A302550 A310117 * A310118 A010335 A310119
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



