I thought I'd mention
that the -12 seems to
be the right answer, because
I am getting -48 + 48 -12 + many zero terms,
so -12 seems right.
I am using a pictoral technique
from post#7 from this forum:
http://www.mathisfunforum.com/viewtopic.php?pid=95302#p95302
(I made that red/black...