Numbers 3:46

And the price you have to give for the two hundred and seventy-three first sons of the children of Israel which are in addition to the number of the Levites,

Exodus 13:13

And for the young of an ass you may give a lamb in payment, or if you will not make payment for it, its neck is to be broken; but for all the first sons among your children, let payment be made.

Numbers 18:15-16

The first birth of every living thing which is offered to the Lord, of man or beast, is to be yours; but for the first sons of man payment is to be made, and for the first young of unclean beasts.

Treasury of Scripture Knowledge

Summary

And for those that are to be redeemed of the two hundred and threescore and thirteen of the firstborn of the children of Israel, which are more than the Levites;

Which are

General references

Bible References

Redeemed

Numbers 18:15
The first birth of every living thing which is offered to the Lord, of man or beast, is to be yours; but for the first sons of man payment is to be made, and for the first young of unclean beasts.
Exodus 13:13
And for the young of an ass you may give a lamb in payment, or if you will not make payment for it, its neck is to be broken; but for all the first sons among your children, let payment be made.

Which are

Numbers 3:39
All the Levites numbered by Moses and Aaron at the order of the Lord, all the males of one month old and over numbered in the order of their families, were twenty-two thousand.

General references

Numbers 3:50
From the first sons of Israel he took it, a thousand, three hundred and sixty-five shekels, by the scale of the holy place;

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain