Xen. A 1 4.9

Xen. A 1 4.9

How do you conjugate σκηνόω and arrive at ἐσκήνουν (presumably 3 pl.) ?
Ancient Greek Conjugator and Wiktionary haven’t got the answer.

The contraction goes like this:
ἐσκήνοον → ἐσκήνουν