Linest() <> Chart Trendline Formula

[MINCUS1308]

I have used the index function to look at the first coefficient of a 3rd degree polynomial.
The data on the graph is the same as what is referenced in the formula.
The formula returned the value 0.0026 the graph trend line shows 0.0004.

The function is as follows:
=INDEX(LINEST((G5:G16)^{1,2,3},,TRUE,FALSE),1)

What is it that I have done wrong?

21299

[p45cal]

A file to play with please…

[MINCUS1308]

Sorry for the delayed response.
Here is the file: 21324

[p45cal]

try:
=INDEX(LINEST(G5:G16,ROW($A$1:$A$12)^{1,2,3},TRUE,FALSE),1)
or:
=INDEX(LINEST(G5:G16,{1;2;3;4;5;6;7;8;9;10;11;12}^{1,2,3},TRUE,FALSE),1)

[MINCUS1308]

Welp, as with most things excel related - I have no idea why but both of those work flawlessly.
Thank you p45cal