Proof. Let Sn be the symmetric Pascal matrix of order n defined by
(1). By Theorem 2.1, we know that Sn = LnUn, where Ln is the lower
triangular Pascal matrix of order n defined by (2) and Un is the upper
triangular Pascal matrix of order n defined by (3). Since Ln and Un
are triangular matrices, then det(Ln) = 1 and det(Un) = 1. It follows
that det(Sn) = det(LnUn) = det(Ln)det(Un) = 1.
Definition 2.3. [5] Let A and B be n × n matrices. We say that
A is similar to B if there is an invertible n × n matrix P such that
P
−1AP = B.