There are 18 padded chairs around a circular table, and the chairs are numbered from 1 through 18 . How many ways can five people take their seats, so that no two people are adjacent?

Where k stands for minmum chair separation between any 2 persons and k<=[n - r] / r and n=number of chairs, r=number of people to be seated and k=1 or number of chairs 2 people must be separated by.