getting around null cell values?

[David Heinrich <dh003i gmail com>]

I have a column with y values that is populated by an IF function like such: IF(B1="","",<calculation>). 

I want to do a polynomial regression on these y values with LINEST so as to get the coefficients for ax^2 + bx + c. Yet, the blank cells screw up LINEST. If I delete the ones that end up blank, LINEST counts them as 0's, and that completely messes up the coefficient calculation. 

Any way to get around this? Any way to populate a series of cells (say B10, B11, B12, B13) with the 4 our of 8 y-value cells in the guys above that contain data, along with the corresponding x-value cells (A10-A13).