Terminology question

[Leroy Quet]

>Consider a set of n numbers a1,...,an.  Form the 2^n sums
>+-a1+-a2+-...+-an, and  examine the frequency of the sums.  Currently, I'm
>calling them extremal sums.  What is this subject called?  Can someone
>point me to some literature?  For a few interesting results along these
>lines, look at http://www.sspectra.com/math/Sums.html
>
>Thanks,
>
>Tony

Sequence A015818 is related, though does not answer your question.

A063865 is also related.

Leroy Quet