Problem

Source: APMO 1996

Tags: combinatorics unsolved, combinatorics



The National Marriage Council wishes to invite $n$ couples to form 17 discussion groups under the following conditions: (1) All members of a group must be of the same sex; i.e. they are either all male or all female. (2) The difference in the size of any two groups is 0 or 1. (3) All groups have at least 1 member. (4) Each person must belong to one and only one group. Find all values of $n$, $n \leq 1996$, for which this is possible. Justify your answer.