# maths

posted by
**keshav** on
.

For how many ordered pairs of positive integers n and k with n and k less than or equal to 20, is the number

((2n)!(2k)!) / (n!k!(n+k)!) an integer?

posted by
**keshav** on
.

For how many ordered pairs of positive integers n and k with n and k less than or equal to 20, is the number

((2n)!(2k)!) / (n!k!(n+k)!) an integer?