How many distinct distributions (x,y,z,w) of n identical marbles in 4 boxes labeled A,B,C and D are there, such that
x,y,z,w are positive integers in strictly increasing order?

Verify the validity of your formula (or set of formulas) by manual listing of all such distributions for n=18.

We are looking for an explicit formula(s) in terms of n?

Posted by chun on 2017-08-16 12:03:20