input "Number of rows: "; rows
dim colSize(rows)
for col=1 to rows
    colSize(col) = len(str$(col + rows * (rows-1)/2))
next

thisNum = 1
for r = 1 to rows
    for col = 1 to r
        print right$( "  "+str$(thisNum), colSize(col)); " ";
        thisNum = thisNum + 1
    next
    print
next