def floyd(n):
    total_width = sum(1 + len(str((n + n * n) / 2 - i)) for i in xrange(0, n)) - 1

    count = 1
    string = ""
    for i in range(1,n+2):
        for j in range(1,i):
            string += " " + str(count)
            count += 1
        print string.center(total_width)
        string = ""

floyd(6)

                 
         1       
        2 3      
       4 5 6     
     7 8 9 10    
  11 12 13 14 15 
 16 17 18 19 20 21