A138220 Numbers k such that 900*k^2 + 1 is prime.

3, 4, 5, 6, 7, 8, 9, 10, 14, 19, 23, 25, 26, 31, 32, 36, 38, 43, 44, 45, 47, 48, 62, 64, 66, 77, 81, 82, 85, 90, 91, 92, 95, 108, 112, 113, 116, 122, 129, 130, 136, 138, 139, 142, 147, 151, 153, 155, 164, 178, 179, 181, 183, 185, 190, 192, 195, 196, 199, 201, 202, 204

Offset: 1

Author

Zak Seidov, May 05 2008

Keywords

• nonn
• easy

Comments

Includes all terms from A125251.

Conjecture: (30*k)^(2^m)+1 is prime for some numbers k at all values of m >= 0. - Richard R. Forberg, Feb 06 2021

Crossrefs

Cf. A125251, A111175, A341183.

Programs

Magma

[n: n in [0..10000]| IsPrime(1+900*n^2)] // Vincenzo Librandi, Dec 13 2010

Mathematica

Select[Range[250],PrimeQ[900#^2+1]&] (* Harvey P. Dale, May 20 2012 *)

PARI

is(n)=isprime(1+900*n^2) \\ Charles R Greathouse IV, Jun 13 2017