Math Question

Does anyone that sees this know if there is a special name for a the property exhibited by a set of integers where any sum of numbers therein (with no repeats) will yield a number unique to all the other possible sums?

i.e. a set exhibiting such a property is {1, 2, 4} because the possible sums are
         1 =1
         2=2
     1+2=3
         4=4
     1+4=5
    2+4=6
1+2+4=7

Anyone?