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 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 (list; graph; refs; listen; history; text; internal format)
 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 * 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

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Last modified November 28 04:31 EST 2021. Contains 349400 sequences. (Running on oeis4.)