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I haven't installed a garage door opener in quite some time. But I would be happy to look at my own opener (which I did install) and tell you how the sensors are wired.
I have 3 terminals on the side of my opener, marked 1, 2, and 3. The sensors each have a low voltage two conductor cable running to them. One conductor for each sensor has a black stripe on it. The black striped conductor for each sensor is connected to terminal number 3. The unstriped conductor for each sensor is connected to terminal number 2.
The wall mounted (hard wired) pushbutton also has a wire connected to terminal number 2. The other wire from the pushbutton is connected to terminal number 1. This gives you 1 wire on terminal number 1, three wires on terminal number 2, and two wires on terminal number 3.