Solution (source code)

= Solution

The factorial-moment argument above gives $Y\Rightarrow\operatorname{Poisson}(\lambda)$ with $\lambda=e^{-c}$. Because $Y$ is integer-valued, apply <convergence in distribution> at the continuity points $3/2$ and $5/2$ and subtract. This proves
$$
\boxed{\mathbb P(Y=2)\longrightarrow e^{-e^{-c}}\frac{e^{-2c}}2.}
$$