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A170951 Numbers n with the property that some of the fractions i/n (with gcd(i,n)=1, 0 < i/n < 1) are in the Cantor set and some are not. 4
9, 12, 13, 27, 28, 30, 36, 39, 40, 81, 82, 84, 90, 91, 108, 117, 120, 121, 243, 244, 246, 252, 270, 273, 324, 328, 351, 360, 363, 364, 729, 730, 732, 738, 756, 757, 810, 819, 820, 949, 972, 984, 1036, 1053, 1080, 1089, 1092, 1093, 2187 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Equals A054591 \ {1,3,4,10}.

The natural numbers may be divided into three sets: denominators which force membership in the Cantor set, denominators which deny membership in the Cantor set and denominators which neither force nor deny membership. The first set contains just the numbers 1, 3, 4, 10. The second set is A170944. The third set is the present sequence.

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

1/9 is in the Cantor set, but 4/9 is not.

CROSSREFS

Cf. A005823, A005836, A054591, A121153, A170943, A170944.

Sequence in context: A295486 A032687 A259313 * A044859 A114306 A009188

Adjacent sequences:  A170948 A170949 A170950 * A170952 A170953 A170954

KEYWORD

nonn,base

AUTHOR

J. H. Conway and N. J. A. Sloane, Feb 20 2010

STATUS

approved

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Last modified October 15 15:14 EDT 2019. Contains 328030 sequences. (Running on oeis4.)