Combinatorics - Painting the Unit Squares of a 3x3 Square

There are $3$ colours for the central square. For each such case we have:-

The four squares adjacent to the central square either consist of

A. $3$ squares of the same colour - $8$ possibilities.

B. $2$ squares of each colour opposite each other- $2$ possibilities.

C. $2$ squares of each colour not opposite each other- $4$ possibilities.

The corner squares can then be chosen in the following number of ways

A. $1$

B. $0$

C. $1$

Total number of arrangements is $3\times (8+4)=36$

N.B. This number will be smaller if we count arrangements which are the same under rotation as actually being the same.