A250181 Numbers n such that Phi_26(n) is prime, where Phi is the cyclotomic polynomial.

2, 3, 21, 22, 23, 35, 39, 74, 80, 84, 89, 108, 114, 121, 126, 134, 152, 153, 171, 180, 195, 204, 230, 256, 263, 297, 321, 326, 336, 342, 345, 351, 368, 390, 393, 397, 398, 399, 413, 427, 439, 490, 525, 563, 566, 574, 591, 602, 609, 630, 641, 652, 657, 660, 667, 682, 685, 694, 708, 712, 716, 721

Offset: 1

Author

R. J. Mathar, Jan 09 2015

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A246397.

Programs

Magma

[n: n in [1..2000]| IsPrime((n^13+1) div (n+1))]; // Vincenzo Librandi, Jan 15 2015

Maple

select(t -> isprime((t^13+1)/(t+1)), [$1..2000]); # Robert Israel, Jan 15 2015

Mathematica

Select[Range[2000], PrimeQ[(#^13 + 1) / (# + 1)] &] (* Vincenzo Librandi, Jan 15 2015 *)

PARI

is(n)=isprime(polcyclo(26,n)) \\ Charles R Greathouse IV, Sep 08 2015