Here is the partly English page of the Norwegian Digital Archives:http://digitalarkivet.uib.no/cgi-win/WebFront.exe?slag=vis&a...
There`s a link there, called "New to the Digital Archive" which would probably help you out - when it gets done... In the meantime there is a "how to" at: http://digitalarkivet.uib.no/sab/howto.html
To search the 1865-census, you`ll need to know these words:
Fornavn = First name
Etternavn = Lastname (mostly the patronym)
Fødselsår = Birthyear
Fødestad = Place of birth
Yrke = Occupation
Gardsnamn = Farm name
lik = same as
børjar på/begynner på = starting with
inneheld/inneholder = contains
A suggestion is using the "starting with", firstname starting with An (covers Ane, Ana, Anna, Anne etc.), lastname starting with T (to cover variations).
Read up on the different links and helpfull pointers you come across on the pages, and get a good Norwegian dictionary (many available online).
Your problem is that you don`t even know if she was born in 1865, we do know she`s not on the Skei farm then. And the 1875 census is not available for your area, AND we don`t know where she was born... Any chance you could find more info on her in the US? Where were they living when she died - would she be buried anywhere close?
I was thinking the T might stand for Tosten, and that she was a niece of Peder Tostensen, maybe daughter of a brother called Tosten Tostensen, but I haven`t been able to verify that.
Keep in mind that the T may also be the first initial in a middle name, and that we may not know anything about her patronym....
If you are sure she is the mother of Albert`s children, wouldn`t you be able to find more info on her on a birthcertificate "over there"?
Just some thoughts... Good luck in your search!