I am travelling on business to Copenhagen at the end of the month and will visit Odense as well. I am planning to reach Odense by train and therefore want to purchase the train tickets online beforehand and print them as soon as I get to Copenhagen. I would also like to book my seat in advance with a table in front of it.
I have visited several sites where they let you purchase the tickets but courier them out to you or give you the option to purchase them through your smartphone.