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 A027757 Numbers k such that k^2 + k + 9 is prime. 4
 1, 4, 13, 16, 19, 25, 28, 43, 49, 55, 76, 79, 88, 106, 118, 121, 139, 145, 151, 154, 175, 190, 205, 208, 211, 235, 238, 253, 259, 268, 271, 301, 310, 370, 373, 376, 391, 400, 403, 415, 433, 445, 484, 490, 508, 511, 523, 544, 568, 580, 583, 589, 610 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..10000 Patrick De Geest, World!Of Numbers MATHEMATICA Select[Range[2500], PrimeQ[#^2 + # + 9] &] (* Harvey P. Dale, Dec 01 2010 *) PROG (Magma) [n: n in [0..1000] |IsPrime(n^2+n+9)] // Vincenzo Librandi, Nov 20 2010 (PARI) is(n)=isprime(n^2+n+9) \\ Charles R Greathouse IV, Feb 20 2017 CROSSREFS Sequence in context: A106681 A144947 A022416 * A287361 A165336 A031181 Adjacent sequences: A027754 A027755 A027756 * A027758 A027759 A027760 KEYWORD nonn AUTHOR Patrick De Geest EXTENSIONS Additional terms from Harvey P. Dale, Dec 01 2010 STATUS approved

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Last modified December 5 10:40 EST 2023. Contains 367589 sequences. (Running on oeis4.)