TOT 1998 Autumn AJ5 20 beads of 10 colours, 2 of each colour, in 10 boxes
Source:
May 11, 2020
Coloringcombinatorics
Problem Statement
There are beads of colours, two of each colour. They are put in boxes. It is known that one bead can be selected from each of the boxes so that each colour is represented. Prove that the number of such selections is a non-zero power of .(A Grishin)