Example: We tile an n-by-1 strip using 1-by-1, 2-by-1 and 3-by-1 tiles. Let to be the number of such tilings. Give a recurrence for ta. Example: Modify the last problem by allowing tiles of two colors, say red and green. Give a recurrence for the number of such tilings. Example: We tile an n-by-1 strip using 1-by-1, 2-by-1 and 3-by-1 tiles. Let to be the number of such tilings. Give a recurrence for ta. Example: Modify the last problem by allowing tiles of two colors, say red and green. Give a recurrence for the number of such tilings