The difference set order of an 
-difference set 
is 
, where 
is a set of 
elements in a group 
of group
order 
and every nonidentity element of 
occurs exactly 
times among the quotients 
for 
with 
.
Difference Set Order
Explore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Difference Set Order." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/DifferenceSetOrder.html