List them in a row.
Then subtract every number from any number that is on
its immediate right, and place that difference between 
and below the numbers that you subtracted, creating a
new row with 1 less number in it.  Then make a new row
doing the same.  Keep doing this until you come to a
row that has all the same numbers in it: 


7   11    10    10    17    37    76
  4    -1     0     7    20    39
    -5     1     7    13    19
        6     6     6     6   

We stop with the third row because it has all 6's

We write another 6 at the end of that row of 6's:

7   11    10    10    17    37    76
  4    -1     0     7    20    39
    -5     1     7    13    19
        6     6     6     6     6

Now work backwards.  Add the 6 to the 19, getting 25.
Place it to the right of the 19

7   11    10    10    17    37    76
  4    -1     0     7    20    39
    -5     1     7    13    19    25 
        6     6     6     6     6

Add the 25 to the 39, getting 64.
Place it to the right of the 39.

7   11    10    10    17    37    76
  4    -1     0     7    20    39    64
    -5     1     7    13    19    25 
        6     6     6     6     6

Add the 64 to the 76 and get 140. 
Place it right of the 76

7   11    10    10    17    37    76   140
  4    -1     0     7    20    39    64
    -5     1     7    13    19    25 
        6     6     6     6     6

The next number is 140.

Edwin