A089373 Numbers k such that k^2 - 7*k + 7 is prime.

0, 7, 10, 12, 15, 16, 22, 25, 27, 31, 36, 37, 40, 46, 51, 52, 55, 57, 60, 61, 67, 75, 85, 87, 90, 97, 102, 106, 111, 120, 136, 151, 156, 157, 162, 171, 172, 177, 180, 186, 192, 202, 205, 211, 220, 222, 225, 237, 240, 241, 250, 255, 261, 267, 271, 277, 282, 286, 291, 292

Offset: 1

Author

Giovanni Teofilatto, Dec 27 2003

Keywords

• easy
• nonn

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..10000

Crossrefs

Cf. A089376 (primes of the form k^2 - 7*k + 7).

Programs

GAP

Concatenation([0],Filtered([7..300],k->IsPrime(k^2-7*k+7))); # Muniru A Asiru, Nov 24 2018

Magma

[0] cat [n: n in [6..300] | IsPrime(n^2 - 7*n + 7)]; // Vincenzo Librandi, Dec 12 2011

Mathematica

Column[(0),Select[Range[6,200],PrimeQ[ #^2-7#+7]&]] (* Vincenzo Librandi, Dec 12 2011 *)

PARI

is(n)=isprime(n^2-7*n+7) \\ Charles R Greathouse IV, May 22 2017

Extensions

More terms from David Wasserman, Sep 15 2005

a(1)=0 inserted by Vincenzo Librandi, Dec 12 2011