A133008 The defining property of the sequences {A, B} = {A000028, A000379} is that they are the unique pair of sets complementary with respect to the positive integers such that p(n) = |{x : x, y in A, x < y, xy = n}| = |{x : x, y in B, x < y, xy = n}| for all n >= 1. The present sequence gives the values of p(n).

0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 2, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 2, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1

Offset: 1

Author

David W. Wilson, Dec 21 2007

Keywords

• nonn

Links

• David W. Wilson, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000028, A000379, A000069, A001969, A133009.

Programs

Haskell

a133008 n = length [x | x <- takeWhile (< n) a000028_list,
                    n `mod` x == 0, let y = n `div` x, x < y,
                    y `elem` takeWhile (<= n) a000028_list]
-- Reinhard Zumkeller, Oct 05 2011