  We prove some properties about the non-zero Taylor series coefficients $a_k$
of the Riemann xi function $\xi(s)$ at $s=\frac{1}{2}$. In particular, we
present integral formulas that evaluate $a_k$ whose integrands involve a
Gaussian function and a function we call $L(x;k)$. We use these formulas to
show that $a_k$ is positive. We also define a sequence of polynomials $p(x;n)$
which arise naturally from the integral formulas and use them to prove that the
coefficients $a_k$ are decreasing.
