what's the equivalent XPath experssion for css selector 'p:nth-of-type(2n)'?

what's the equivalent XPath experssion for css selector 'p:nth-of-type(2n)'?

explantion of css selector ':nth-of-type', see
http://www.w3.org/TR/2001/WD-css3-selectors-20010126/#selectors
is it possiable to transform css selector 'p:nth-of-type(2n)' to
equivalent XPath experssion ?
anybody help ?