Sloping Binary Numbers: A New Sequence Related to the Binary Numbers
  If the list of binary numbers is read by upward-sloping diagonals, the resulting ``sloping binary numbers'' 0, 11, 110, 101, 100, 1111, 1010, ... (or 0, 3, 6, 5, 4, 15, 10, ...) have some surprising properties. We give formulae for the n-th term and the n-th missing term, and discuss a number of related sequences. 
David Applegate, Benoit Cloitre, Philippe Del\'eham, N. J. A. Sloane