When do linear combinations of orthogonal polynomials yield new sequences of orthogonal polynomials?

M. Alfaro, F. Marcellan, A. Pena +1

Given $\{P_n\}$ a sequence of monic orthogonal polynomials, we analyze their linear combinations $\{Q_n\}$with constant coefficients and fixed length $k+1$. Necessary and suffici…