This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A173933 #12 Jul 20 2019 11:07:30 %S A173933 1,2,3,3,4,8,6,15,6,6,8,15,8,12,8,8,10,24,27,16,12,9,63,10,16,12,63, %T A173933 20,12,11,10,36,12,56,12,12,44,12,15,36,12,16,120,60,110,24,16,18,24, %U A173933 225 %N A173933 The number of numbers m < k/2 such that m/k is a reduced fraction in the Cantor set, where k= A173931(n). %C A173933 When k is a prime of the form (3^r-1)/2, then the m are 2^r-1 numbers (greater than 0) whose base-3 representation consists of only 0's and 1's. Hence, for r=3,7, and 13, the primes k are 13, 1093, and 797161, and the number of m < k/2 is 3, 63, and 4095. %H A173933 T. D. Noe, <a href="/A173933/b173933.txt">Table of n, a(n) for n = 1..185</a> %e A173933 When k=40, then 1/k, 3/k, 9/k, and 13/k have base-3 representations containing only the digits 0 and 2. %t A173933 Length /@ Last[Transpose[cantor]] (* see A173931 *) %Y A173933 Cf. A005823, A005836, A007734, A076481, A173931, A173934. %K A173933 nonn %O A173933 1,2 %A A173933 _T. D. Noe_, Mar 03 2010 %E A173933 Name qualified by _Peter Munn_, Jul 14 2019