A027757 Numbers k such that k^2 + k + 9 is prime.

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

Offset: 1

Author

Patrick De Geest

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000
• Patrick De Geest, World!Of Numbers

Programs

Magma

[n: n in [0..1000] |IsPrime(n^2+n+9)] // Vincenzo Librandi, Nov 20 2010

Mathematica

Select[Range[2500], PrimeQ[#^2 + # + 9] &] (* Harvey P. Dale, Dec 01 2010 *)

PARI

is(n)=isprime(n^2+n+9) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

Additional terms from Harvey P. Dale, Dec 01 2010