Tests memory trend calculation.

initial: count=0 slope=0
(1, 1):  count=1 slope=0
(2, 2):  count=2 slope=1
(3, 4):  count=3 slope=1.5
(4, 5):  count=4 slope=1.4
(5, 5):  count=4 slope=1
(6, 4):  count=4 slope=0
(7, 3):  count=4 slope=-0.7
(9, 1):  count=4 slope=-1