Sociable numbers computed using the analog of the restricted divisor function 
in which only unitary divisors are included.
Unitary Sociable Numbers
See also
Sociable NumbersExplore with Wolfram|Alpha
References
Guy, R. K. "Unitary Aliquot Sequences." §B8 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 63-65, 1994.Referenced on Wolfram|Alpha
Unitary Sociable NumbersCite this as:
Weisstein, Eric W. "Unitary Sociable Numbers." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/UnitarySociableNumbers.html