A111052 Numbers m such that 3*m^2 + 4 is prime.

1, 3, 5, 7, 11, 19, 21, 25, 31, 33, 37, 39, 45, 49, 53, 73, 75, 77, 81, 89, 91, 93, 107, 115, 119, 129, 131, 135, 137, 145, 157, 185, 187, 193, 203, 205, 207, 213, 215, 221, 227, 229, 231, 249, 259, 261, 263, 271, 283, 291, 297, 299, 301, 317, 325, 327, 331

Offset: 1

Author

Parthasarathy Nambi, Oct 06 2005

Keywords

• nonn
• easy

Examples

			If m=77 then 3*m^2 + 4 = 17791 (prime).
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A201477.

Programs

Magma

[n: n in [1..350] | IsPrime(3*n^2+4)]; // Vincenzo Librandi, Feb 06 2016

Mathematica

Select[Range[340], PrimeQ[3*#^2 + 4] &] (* Stefan Steinerberger, Feb 26 2006 *)

PARI

lista(nn) = {for(n=1, nn, if(ispseudoprime(3*n^2 + 4), print1(n, ", ")));} \\ Altug Alkan, Feb 05 2016

Formula

a(n) = sqrt((A201477(n)-4)/3). - Zak Seidov, Feb 04 2016

Extensions

More terms from Stefan Steinerberger, Feb 26 2006