A125603 Numbers n such that 3n(n-1)/2 + 1 is prime.

4, 5, 9, 12, 17, 20, 21, 24, 32, 37, 40, 45, 49, 56, 57, 69, 72, 77, 81, 84, 85, 96, 100, 104, 105, 109, 116, 117, 125, 132, 136, 140, 141, 145, 152, 157, 164, 165, 169, 172, 181, 185, 189, 192, 196, 204, 205, 216, 217, 220, 221, 224, 245, 257, 264, 269, 272, 277

Offset

1,1

Links

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

Mathematica

Select[Range[300], PrimeQ[3# (#-1)/2+1]&] (* Harvey P. Dale, Mar 09 2017 *)

Prog

(PARI) isok(n) = isprime(3*n*(n-1)/2 + 1); \\ Michel Marcus, Oct 11 2013

Crossrefs

Cf. A005448, A125602.

Sequence in context: A228914 A200535 A010405 * A239231 A078507 A060199

Adjacent sequences: A125600 A125601 A125602 * A125604 A125605 A125606

Keyword

nonn

Author

Zak Seidov, Nov 27 2006

Status

approved