Closed form for generating function of Riemann Xi function

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What is the closed form for

$$f(x)=\ \sum_{k=1}^\infty \frac{\xi(k)x^k}{k!}$$

or

$$g(x)=\frac12 \sum_{k=1}^\infty \frac{\xi(k+1/2)x^k}{k!}$$

or

$$w(x)=\frac12 \sum_{k=1}^\infty \frac{\xi(k+1/2)x^k}{(k^2-1/4)k!}$$

?