a(n)=denominator of the probability that (x-y)/(x+y)+(y-z)/(y+z)+(z-u)/(z+u)+ (u-x)/(u+x) >0, assuming that each random quadruple of integers (x,y,z,u), with a<=x,y,z,u<=n, is equally likely.

A106200

a(n)=denominator of the probability that (x-y)/(x+y)+(y-z)/(y+z)+(z-u)/(z+u)+ (u-x)/(u+x) >0, assuming that each random quadruple of integers (x,y,z,u), with a<=x,y,z,u<=n, is equally likely.