Hi I'm trying to figure out how many combinations with the the following 8 items, I can make.

Let's say that I have the following items in two colors each (blank and White): triangle, circle, square and two rectangles with the same color (no white, no black), let's say red.

rules:

1) two items of the same type cannot be together. for instance a black triangle and white triangle cannot be next to each other.

2) any combination starting with a rectangle is not allowed.

3) the first 4 elements of any of the combinations must be identical to the second half (5 to8)but with the opposite color. For instance: black circle, white triangle, black square, rectangle, white circle, black triangle, white square, rectangle.

4) reversed combinations based on color are not needed. for instance if we take the above combination and reverse it:white circle, black triangle, white square, rectangle,black circle, white triangle, black square, rectangle. We only need one of these combinations but not both.

when I'm doing the calculation. I'm thinking of C4,4 = 4x3=12

but because I have to ignore all combinations starting with rectangle. the number should be 8 posible combinations. is this correct?

However, for some reason I think there can't be 8 posible combinations but actually probably only 4.

is this correct?