I am sorry for your loss. The answer to your question is yes, according to Norwegian law children are entitled to at least 2/3 of the estate of their parent (if there is more than one child they share the 2/3 between them), after any surviving spouse has received an appropriate share (usually 1/3).
This happens even if there is a Will, because under Norwegian law a person may not disinherit a child even through a Will. Thus, if there is no Will and no spouse children receive the entire estate.
Therefore, I strongly suggest you inquire about your father's estate sooner rather than later, because you should have an entitlement over it.
The practical problem with Norway is that it is not a party to the EU Succession Regulation, nor does it have a register of Wills kept by notaries as other European countries do. Therefore, unless you live in the Nordic Countries as well (there is a 1934 Nordic Convention which can facilitate bureaucracy in such a case), you will have to inquire directly with a local attorney to make the necessary procedures and searches on the ground (property register search, business register for any company to his name etc.).
As I am not allowed to make representations via JA, I would like to point to the testament.no website, which is part of a network (norjus.no) which can provide such assistance, but it is only an example. Also, you may find English-apeaking attorneys qualified in Norway here: http://photos.state.gov/libraries/norway/45384/amcit/Lawyers%20list%20revised%202012.pdf
I hope my answer helped you and look forward to your rating which is essential to my activity.
Dr I L Vlad