*      declare space for the pascal triangle up to n = 20.
      integer  tab (0:20,0:20)

*        open the output file for the pascal triangle.
      open(1,file='binom.tab',status='unknown')

*         Make sure the output file is at beginning of file.
*         This is really a redundant operation under the unix system.
      rewind 1

*         Fill the left edge of the triangle
      do 1 n = 0,20
      tab(n,0) = 1
    1 continue

*         Complete the second row of the triangle.
      tab(1,1) = 1

*        complete the triangle for rows 2 through 20.
      do 4 n = 2,20
      do 3 j = 1,n
      tab(n,j) = tab(n-1,j-1) + tab(n-1,j)
    3 continue
    4 continue

*         write out the triangle.
      do 5 n = 0,20
      write(1,8)n
      m1 = min0(5,n)
      write(1,6)(j,j=0,m1)
      write(1,6)( tab(n,j),j=0,m1)
      write(1,*)
      if(m1.eq.n)go to 5
      m2 = min0(10,n)
      write(1,7)(j,j=6,m2)
      write(1,7)( tab(n,j),j=6,m2)
      write(1,*)
      if(m2.eq.n)go to 5
      m3 = min(15,n)
      write(1,7)(j,j=11,m3)
      write(1,7)( tab(n,j),j=11,m3)
      write(1,*)
      if(m3.eq.n)go to 5
      m4 = min(20,n)
      write(1,7)(j,j=16,m4)
      write(1,7)( tab(n,j),j=16,m4)
      write(1,*)
    5 continue 
    6 format(10x,6i10)
    7 format(20x,5i10)
    8 format(' N = ',i5)
      rewind 1
      stop
      end