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 A089593 Numbers k such that k^2 + 2k + 2 is prime. 1
 0, 1, 3, 5, 9, 13, 15, 19, 23, 25, 35, 39, 53, 55, 65, 73, 83, 89, 93, 109, 115, 119, 123, 125, 129, 133, 145, 149, 155, 159, 169, 175, 179, 183, 203, 205, 209, 223, 229, 235, 239, 249, 255, 259, 263, 269, 279, 283, 299, 305, 313, 325, 339, 349 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988 Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A005574(n)-1 = A090693(n)-2. MATHEMATICA Select[Range[0, 1000], PrimeQ[#^2+2#+2]&] (* Vincenzo Librandi, May 23 2014 *) PROG (Magma)[n: n in [0..400]|IsPrime(n^2+2*n+2)]; // Vincenzo Librandi, Dec 17 2010 (PARI) is(n)=isprime(n^2+2*n+2) \\ Charles R Greathouse IV, Jun 12 2017 CROSSREFS Cf. A002496 gives the primes, A005574, A090693. Sequence in context: A177078 A187906 A187229 * A204663 A191129 A018533 Adjacent sequences: A089590 A089591 A089592 * A089594 A089595 A089596 KEYWORD nonn,easy AUTHOR Giovanni Teofilatto, Dec 30 2003 EXTENSIONS Corrected by Vincenzo Librandi, Dec 17 2010 STATUS approved

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Last modified April 18 15:48 EDT 2024. Contains 371780 sequences. (Running on oeis4.)