The problem can be thought of as distinct permutations of the letters GGGYY; that is arrangements of 5 letters, where 3 letters are similar, and the remaining 2 letters are similar: The number of perm...The problem can be thought of as distinct permutations of the letters GGGYY; that is arrangements of 5 letters, where 3 letters are similar, and the remaining 2 letters are similar: The number of permutations of n elements taken n at a time, with r1 elements of one kind, r2 elements of another kind, and so on, such that n=r1+r2+…+rk is
