How many solutions are there to the equation u + v + w + x + y + z = 18 where u, v, w, x, y, and z are nonnegative integers, and x is at most 10?
a=listfor(n, 1, 11, (11+n) nCr 4);print a, "=", sum a
(495, 715, 1001, 1365, 1820, 2380, 3060, 3876, 4845, 5985, 7315) = 32857 - total number of solutions.
