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 A242029 #15 Aug 19 2014 01:01:38
%S A242029 0,0,1,1,2,0,3,2,1,2,3,1,4,2,1,2,5,2,3,2,1,4,5,1,4,2,3,4,3,0,5,6,3,2,
%T A242029 3,0,5,6,3,3,4,2,5,2,3,4,5,2,5,4,1,6,7,0,3,2,3,6,7,3,4,4,3,2,3,2,9,6,
%U A242029 1,2,5,4,7,4,1,4,7,2,3,4,3,6,7,1,6,4,5
%N A242029 Number of anti-divisors m <= n of n that are coprime to n.
%C A242029 See A066272 for the definition of anti-divisor; that sequence gives the number of anti-divisors m < n of n.
%C A242029 All the anti-divisors m < n of prime n must be coprime to n, since any integer k > 1 must either divide or be coprime to prime n, and since no anti-divisor m can divide n.
%H A242029 Michael De Vlieger, <a href="/A242029/b242029.txt">Table of n, a(n) for n = 1..10000</a>
%H A242029 M. De Vlieger, <a href="http://www.vincico.com/proof/antidivisors.html">Arithmetic Relationships between Antidivisors k < n and n</a>
%e A242029 a(3) = 1 and A066272(3) = 1 because the set of anti-divisors of 3 = {2} and 2 is coprime to 3.
%e A242029 a(6) = 0 and A066272(6) = 1 because the set of anti-divisors of 6 = {4} but 4 is not coprime to 6.
%e A242029 a(12) = 1 and A066272(12) = 2 because the set of anti-divisors of 12 = {5, 8}, but only 5 is coprime to 12.
%t A242029 antiDivisors[n_Integer] := Cases[Range[2, n - 1], _?(Abs[Mod[n, #] - #/2] < 1 &)]; a242029[n_Integer] := Length[Select[antiDivisors[n], CoprimeQ[#, n] &]]; Table[a242029[k], {k, 100}] (* _Michael De Vlieger_, Aug 11 2014 *)
%Y A242029 Cf. A066272, A240979.
%K A242029 nonn
%O A242029 1,5
%A A242029 _Michael De Vlieger_, Aug 11 2014