Beck, W. E. and Najar, R. M. "More Reduced Amicable Pairs." Fib. Quart.15, 331-332, 1977.Guy,
R. K. "Quasi-Amicable or Betrothed Numbers." §B5 in Unsolved
Problems in Number Theory, 2nd ed. New York:Springer-Verlag, pp. 59-60,
1994.Hagis, P. and Lord, G. "Quasi-Amicable Numbers." Math.
Comput.31, 608-611, 1977.Sloane, N. J. A. Sequence
A005276/M5291 in "The On-Line Encyclopedia
of Integer Sequences."