Question 1041860
It is (14-2k) where k runs from 3 to 15.  It has a sum.
The first term is 14-2(3)=8
The second term is 14-2(4)=6
so the terms are
8,6,4,2,0,-2,-4,-6,-8,-10,-12,-14,-16
The sum may be computed by canceling 2 and -2 up to 8 and -8
The remaining terms are -10,-12,-14,-16, and they add to -52.