A250182 Numbers n such that Phi_28(n) is prime, where Phi is the cyclotomic polynomial.

4, 5, 7, 13, 25, 33, 41, 63, 74, 80, 88, 94, 96, 104, 116, 144, 149, 151, 154, 165, 167, 174, 183, 191, 197, 208, 231, 241, 262, 268, 270, 290, 318, 319, 361, 368, 376, 390, 394, 412, 431, 434, 442, 464, 489, 492, 521, 529, 556, 568, 574, 575, 585, 589, 613, 629, 639, 654, 666, 667, 672, 683, 684

Offset: 1

Author

R. J. Mathar, Jan 09 2015

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A246392.

Programs

Mathematica

Select[Range[700], PrimeQ[Cyclotomic[28, #]] &] (* Vincenzo Librandi, Jan 17 2015 *)

PARI

isok(n) = isprime(polcyclo(28, n)); \\ Michel Marcus, Jan 17 2015