How many solutions are there to the equation u+v+w+x+y+z=10 where u, v, w, x, y, and z are nonnegative integers, and x is at most 2?
a=listfor(n, 1, 3, (11+n) nCr 4);print a, "=", sum a
(495, 715, 1001) = 2211 - total number of solutions.
