A250181 - OEIS

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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

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OFFSET

1,1

LINKS

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

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 *)

PROG

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

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