A176545 Numbers k>0 such that 2*k^2+14*k+5 is prime.

2, 9, 11, 12, 14, 17, 21, 24, 26, 39, 44, 47, 59, 77, 86, 87, 89, 101, 116, 117, 122, 126, 131, 137, 147, 152, 161, 164, 177, 179, 189, 191, 192, 201, 212, 219, 222, 231, 249, 257, 261, 264, 284, 287, 296, 306, 317, 326, 329, 336, 347, 369, 387, 389, 411, 417

Offset: 1

Author

Vincenzo Librandi, Apr 20 2010

Keywords

• nonn
• easy

Comments

Conjecture: If p = 2*k^2 + 14*k + 5 then 2^p - 1 is not prime.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A154577 (Primes of the form 2n^2 + 14n + 5), A144562(Triangle read by rows where T(m, n) = 2m*n + m + n - 1).

Programs

Magma

[n: n in [1..1000]| IsPrime(2*n^2+14*n+5)];

Mathematica

Select[Range[500], PrimeQ[2#^2 + 14# + 5] &] (* Harvey P. Dale, Jan 09 2011 *)