Usage: 2 forms in 8 verses
Form Translated As     In Verse(s)
δεκατριών thirteen LXX.Gen.17.25LXX.Ezek.40.11
δεκατρείσ thirteen LXX.Josh.18.28LXX.Josh.19.6LXX.Josh.21.4LXX.Josh.21.6LXX.Josh.21.19LXX.Josh.21.33

Liddell-Scott-Jones

δεκατρεῖς (dekatreis) thirteen TEGMC

δεκατρεῖς, οἱ, αἱ, τριακαίδεκα, τά,

first as three words, later as one, thirteen: genitive τριῶν καὶ δέκα [Refs 5th c.BC+]:—sts other words are interposed, τρεῖς τε καὶ δ. [Refs 5th c.BC+] — the form τρισκαίδεκα (_accusative_ _masculine_ and _feminine_) is found in codices of [δεκατρεῖς, διὰ διφθόγγου γράφουσι τὰ τῶν ἀντιγράφων ἀκριβέστερα 12th c.AD: Eustathius Episcopus Thessalonicensis (at [prev. work])); also of 5th c.BC: Pindarus Lyricus “Fragmenta.” 135 (variant), 5th c.BC: Bacchylides Lyricus [prev. cited] (Papyrus), 5th-6th c.BC: Aristophanes Comicus “Ranae” 50, 5th-6th c.BC: Xenophon Historicus “Historia Graeca (Hellenica)” 5.1.5, 5th c.BC: Thucydides Historicus 3.69, 79, 8.88 (τρεῖς καὶ δέκα codex B)">Refs 8th c.BC+]; τρισκαίδεκα as genitive, [Refs 5th c.BC+]; στατῆρας δεκατρεῖς [Refs 4th c.BC+]; τρε[ισκαί]δεκα πόλεων [Refs 3rd c.BC+]; λίθων δεκατρεῖς [Refs 2nd c.BC+]; so that τρισκαίδεκα should be corrected in all early texts (in spite of [δεκατρεῖς: the same applies to the following compounds: see at {τρεισκαιδέκατος}. ">Refs 4th c.AD+]