ei krone · krone (Norwegian currency)
Feminine (ei)
Indefinite singular
ei krone
Definite singular
krona
Indefinite plural
kroner
Definite plural
kronene
Feminine nouns (ei) can always be written with en as well: ei bok, boka or en bok, boken. Both are correct Bokmål.
How to guess the gender Nouns: gender and articles