A250187 Numbers n such that Phi(38,n) is prime, where Phi is the cyclotomic polynomial.

2, 10, 13, 24, 28, 43, 47, 49, 54, 65, 83, 98, 106, 143, 152, 177, 184, 190, 194, 195, 241, 249, 259, 264, 292, 315, 319, 345, 353, 355, 386, 394, 481, 500, 517, 525, 534, 535, 556, 595, 601, 649, 656, 680, 686, 687, 697, 707, 710, 756, 798, 804, 817, 818, 829, 839, 841, 858, 864, 891, 906, 912, 932, 948, 973, 991, 994, 1012

Offset: 1

Author

R. J. Mathar, Jan 12 2015

Keywords

• nonn

Links

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

Crossrefs

Cf. A246392.

Programs

Magma

[n: n in [1..2000]| IsPrime((n^19+1) div (n+1))]; // Vincenzo Librandi, Jan 15 2015

Mathematica

Select[Range[2000], PrimeQ[(#^19 + 1) / (# + 1)] &] (* Vincenzo Librandi, Jan 15 2015 *)

PARI

select(x->isprime(x), vector(1000, n, polcyclo(38, n)), 1) \\ Michel Marcus, Jan 15 2015