Declension table of pitṛ

Masculine	Singular	Dual	Plural
Nominative	pitā	pitarau	pitaraḥ
Vocative	pitaḥ	pitarau	pitaraḥ
Accusative	pitaram	pitarau	pitṝn pitaraḥ
Instrumental	pitrā	pitṛbhyām	pitṛbhiḥ
Dative	pitre	pitṛbhyām	pitṛbhyaḥ
Ablative	pituḥ	pitṛbhyām	pitṛbhyaḥ
Genitive	pituḥ	pitroḥ	pitṝṇām
Locative	pitari	pitroḥ	pitṛṣu

Compound pitā - pitṛ -

Adverb -pitṛ