As far as I know they are not counted.
Well technically they are counted and listed, but when the division of seats come into play they are not counted so ultimately you are giving more votes to the majority.
But someone like ghoti or Paul can confirm this as I'm no expert.
Can you explain your logic here. I've often heard people say that not voting means giving more votes to the majority but that statement doesn't make any sense to me at all and nobody has ever been able to explain why they think that.