I came here just to see if someone had already shared that song and I'm not disappointed.
It is "en hytte" (or "ei hytte") in the indefinite form, and hytten (or hytta) in definite, depending on the gender you use. The difference between the "e" and the "a" ending that though in both cases you form your mouth to say an A with a very open throat, in case of "e" you add a spice of an E (like the first E in "ever"), so it sounds like the "i" in "like", or "o" in "our", and so on. The "a" in "hytta" is much more like the "oo" in "blood". I had a hard time explaining as English isn't my native language, and both of those sounds in Norwegian are part of my own native tounge... :D I'm sorry if it's a bit confusing, I did my best. :')
It does sound like an 'a' but it's kinda like a cut off 'e'. It's like you're pronouncing the letter 'e' but you cut it short, so it ends up sounding like an 'a'.
That's how I make the sound. Someone knowledgeable on IPA might know how to explain better, though.