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 A250181 Numbers n such that Phi_26(n) is prime, where Phi is the cyclotomic polynomial. 18
 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 (list; graph; refs; listen; history; text; internal format)
 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 CROSSREFS Cf. A246397. Sequence in context: A132500 A129411 A124447 * A024765 A282340 A248953 Adjacent sequences: A250178 A250179 A250180 * A250182 A250183 A250184 KEYWORD nonn AUTHOR R. J. Mathar, Jan 09 2015 STATUS approved

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Last modified February 1 10:32 EST 2023. Contains 359993 sequences. (Running on oeis4.)