Table Triangular Rectangular

Under.zip (XTable) "TableTriangularRectangular" - Creates a triangular table in your document.
You can specify the number of cells in the base row; each successive row will have one fewer cells; the final row will have one cell.

You specify a negative value for rows go from once cell to the number of cells, a positive value to go from the number of cells to one cell.

This is similar to "TableTriangular" in that the number of cells varies with each row, but the entire table has a rectangular outline.