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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

%I #4 Mar 30 2012 16:51:55

%S 1,4,10,12,13,28,30,36,39,40,82,84,90,91,108,117,120,121,244,246,252,

%T 270,273,324,328,351,360,363,364,730,732,738,756,757,810,819,820,949,

%U 972,984,1036,1053,1080,1089,1092,1093,2188,2190,2196,2214,2268,2271,2362,2430

%N 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.

%C That is, neither of the two representations of 1/n in base 3 contain a 1.

%C This is A121153 without the numbers 3^k, k >= 1. See that entry for further information.

%H T. D. Noe and N. J. A. Sloane, <a href="/A170943/b170943.txt">Table of n, a(n) for n=1..1144</a> (terms < 3^21)

%e 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.

%e 1/4 in base 3 is .02020202020..., so 4 is in the sequence.

%Y Cf. A005823, A005836, A121153, A170951.

%K nonn,base

%O 1,2

%A J. H. Conway, T. D. Noe and _N. J. A. Sloane_, Feb 20 2010