Christmas combinatorics

Created
Wed, 21/12/2022 - 20:49
Updated
Wed, 21/12/2022 - 20:49
Yours truly has invited five of his colleagues to share a Christmas lunch with him around the circular dinner table in his kitchen. Unfortunately, two of the colleagues are not on speaking terms with each other, so they cannot be seated together. In how many ways can we be seated around the table?