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 A250176 Numbers n such that Phi_20(n) is prime, where Phi is the cyclotomic polynomial. 3
 4, 9, 11, 16, 19, 26, 34, 45, 54, 70, 86, 91, 96, 101, 105, 109, 110, 119, 120, 126, 129, 139, 141, 149, 171, 181, 190, 195, 215, 229, 260, 276, 299, 305, 309, 311, 314, 319, 334, 339, 369, 375, 414, 420, 425, 444, 470, 479, 485, 506, 519, 534, 540, 550 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS G. C. Greubel, Table of n, a(n) for n = 1..10000 MATHEMATICA Select[Range[600], PrimeQ[Cyclotomic[20, #]] &] (* Vincenzo Librandi, Jan 16 2015 *) PROG (PARI) isok(n) = isprime(polcyclo(20, n)); \\ Michel Marcus, Sep 29 2015 CROSSREFS Cf. A008864 (1), A006093 (2), A002384 (3), A005574 (4), A049409 (5), A055494(6), A100330 (7), A000068 (8), A153439 (9), A246392 (10), A162862(11), A246397 (12), A217070 (13), A006314 (16), A217071 (17), A164989(18), A217072 (19), A217073 (23), A153440 (27), A217074 (29), A217075(31), A006313 (32), A097475 (36), A217076 (37), A217077 (41), A217078(43), A217079 (47), A217080 (53), A217081 (59), A217082 (61), A006315(64), A217083 (67), A217084 (71), A217085 (73), A217086 (79), A153441(81), A217087 (83), A217088 (89), A217089 (97), A006316 (128), A153442(243), A056994 (256), A056995 (512), A057465 (1024), A057002 (2048), A088361 (4096), A088362 (8192), A226528 (16384), A226529 (32768), A226530(65536). Sequence in context: A243178 A312834 A312835 * A312836 A312837 A190547 Adjacent sequences: A250173 A250174 A250175 * A250177 A250178 A250179 KEYWORD nonn AUTHOR Eric Chen, Dec 24 2014 EXTENSIONS More terms from Vincenzo Librandi, Jan 16 2015 STATUS approved

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Last modified September 26 07:08 EDT 2023. Contains 365653 sequences. (Running on oeis4.)