A089593 Numbers k such that k^2 + 2k + 2 is prime.

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

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