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 A175593 Numbers n such that 2n has no primitive root but 2n-1 and 2n+1 both have primitive roots. 0
 4, 6, 12, 14, 15, 21, 24, 30, 36, 40, 51, 54, 63, 69, 75, 84, 90, 96, 99, 114, 120, 135, 141, 156, 174, 180, 210, 216, 231, 261, 285, 300, 309, 321, 330, 364, 405, 411, 414, 420, 429, 441, 510, 516, 525, 531, 546, 576, 615, 639, 645, 651, 660, 684, 714, 726, 741 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA {n: A046145(2n)=0 and A046145(2n-1)>0 and A046145(2n+1)>0}. EXAMPLE 4 is in the sequence because 8 is not in A033948 but 7 and 9 are. CROSSREFS Cf. A033948, A046145. Sequence in context: A310593 A310594 A310595 * A163097 A110178 A318712 Adjacent sequences:  A175590 A175591 A175592 * A175594 A175595 A175596 KEYWORD nonn AUTHOR Vladislav-Stepan Malakhovsky and Juri-Stepan Gerasimov, Jul 20 2010 STATUS approved

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Last modified October 13 22:31 EDT 2019. Contains 327983 sequences. (Running on oeis4.)