One of the polynomials obtained by taking powers of the Brahmagupta matrix. They satisfy the recurrence relation

A list of many others is given by Suryanarayan (1996). Explicitly,

The Brahmagupta polynomials satisfy

The first few polynomials are

and

Taking and gives equal to the Pell numbers and equal to half the Pell-Lucas numbers. The Brahmagupta polynomials are related to the Morgan-Voyce polynomials, but the relationship given by Suryanarayan (1996) is incorrect.

More things to try:

Weisstein, Eric W. "Brahmagupta Polynomial." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/BrahmaguptaPolynomial.html