A250187 - OEIS

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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

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OFFSET

1,1

LINKS

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

MATHEMATICA

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

PROG

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

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

CROSSREFS

Cf. A246392.