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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
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
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.)