Statistics or Mathematics, Sir,

please help me to find any math formula to solve this PROGressive count for
my2007 workbook.
i need to count in a cumulative manner the mid-match of 2 column-row data in
COL.A and COL.B.
-----------------------------------------------
Table 1 Reference for math mid-match
COL.A COL.B COL.C COL.D

b 2
d 4
f 6
a 8
c 10
------------------------------------------------------------------------------------------Table 2 Value for math mid-match
COL.A COL.B COL.C COL.D

a 1 =count = 0
b 2 =count = 0
c 3 1 =count = 1 [c,3] b/w [b,2] & [d,4]
d 4 =count = 1
e 5 1 =count = 2 [ cum. sum]
f 6 =count = 2
g 7 1 =count = 3
a 8 =count = 3
b 9 1 =count = 4
c 10 =count = 4
d 11 =count = 4
e 12 =count = 4
f 13 =count = 4
g 14 =count = 4

formula, to replace Col.D without a helper column COL.C.
Note Col.C is if formulated to provide either 1 or a blank result.
Table 2 Col.A is a looping series from a to g. Col.B with any numeric or
date series value.
thanks for any reply with a formula or whatever.
been dribled to 2007