SB 4.1.61
tebhyo ’gnayah samabhavan
catvarimsac ca pañca ca
ta evaikonapañcasat
sakam pitr-pitamahaih
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
From those three sons another forty-five descendants were generated, who are also fire-gods. The total number of fire-gods is therefore forty-nine, including the fathers and the grandfather.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The grandfather is Agni, and the sons are Pavaka, Pavamana and Suci. Counting these four, plus forty-five grandsons, there are altogether forty-nine different fire-gods.