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 A170943 Numbers n with the property that when 1/n is written in base 3 (in either of the two representations, if the representation is ambiguous) the fractional part contains no 1's. 5
 1, 4, 10, 12, 13, 28, 30, 36, 39, 40, 82, 84, 90, 91, 108, 117, 120, 121, 244, 246, 252, 270, 273, 324, 328, 351, 360, 363, 364, 730, 732, 738, 756, 757, 810, 819, 820, 949, 972, 984, 1036, 1053, 1080, 1089, 1092, 1093, 2188, 2190, 2196, 2214, 2268, 2271, 2362, 2430 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS That is, neither of the two representations of 1/n in base 3 contain a 1. This is A121153 without the numbers 3^k, k >= 1. See that entry for further information. LINKS T. D. Noe and N. J. A. Sloane, Table of n, a(n) for n=1..1144 (terms < 3^21) EXAMPLE 1/3 in base 3 can be written as either .1 or .0222222... The first version contains a 1, so 3 is not in the sequence. 1/4 in base 3 is .02020202020..., so 4 is in the sequence. CROSSREFS Cf. A005823, A005836, A121153, A170951. Sequence in context: A090070 A078005 A092428 * A102998 A071179 A155475 Adjacent sequences:  A170940 A170941 A170942 * A170944 A170945 A170946 KEYWORD nonn,base AUTHOR J. H. Conway, T. D. Noe and N. J. A. Sloane, Feb 20 2010 STATUS approved

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Last modified June 13 20:25 EDT 2021. Contains 345009 sequences. (Running on oeis4.)