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URL: https://oeis.org/A250176

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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
OFFSET
1,1
LINKS
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: A312834 A312835 A387864 * A312836 A312837 A190547
KEYWORD
nonn
AUTHOR
Eric Chen, Dec 24 2014
EXTENSIONS
More terms from Vincenzo Librandi, Jan 16 2015
STATUS
approved