Given an amicable pair 
, the quantity
 |  |  |
(1)
|
 |  |  |
(2)
|
 |  |  |
(3)
|
is called the pair sum, where 
is the divisor function and 
is the restricted
divisor function.
Pair Sum
See also
Amicable PairExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Pair Sum." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PairSum.html