Analyzing General Full Factorial

I'm trying to analyze a 4 factor 3 level general full factorial in
MINITAB. I'm getting results but I can't figure out what terms they
are.

Here is a simplified example. I'm using two factors A and B. A has
four levels and B has three levels. (A = 1,2,3,4 and B=1,2,3). The
analysis only uses the A term. I have dummied the output to be A^2.
This is the output from MINITAB.

Term Coef SE Coef T P
Constant 7.50000 0.00000 * *
A
1 -6.50000 0.00000 * *
2 -3.50000 0.00000 * *
3 1.50000 0.00000 * *

I would think that this means:

7.5+ -6.5*A - 3.5*A^2 + 1.5*A^3.

However it SHOULD be simply A^2.

What the heck is MINITAB trying to tell me?

Thanks!!

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