## Problem of the Week 965## Ten Four-Letter WordsUsing the letters A and B one can form ten four-letter words, if we exclude those having three consecutive letters the same. How many ways are there to place the letters A and B in the spaces of a 4 x 4 grid so that the 4 rows reading left to right, the 4 columns reading top to bottom, and the two diagonals (reading down) consist of the ten words specified. Source: P98 in the just-released book |

26 September 2002