1. 3705
2. Todd J. The problem of error in digital computation. In: Rall LB editors. Error in digital computation. John Wiley & Sons Inc. New York 1965; Vol. I. p. 3–41.
3. Barry P. Sequence A166645 at OEIS (On-Line Encyclopedia of Integer Sequences).
4. Kimberling C. Sequence A025276 at OEIS (On-Line Encyclopedia of Integer Sequences).