Solution
= Solution
For $n\geq1$, the ratio of positive terms is
$$
\frac{(n+1)^4e^{-(n+1)^2}}{n^4e^{-n^2}}=\left(1+\frac1n\right)^4e^{-2n-1}\longrightarrow0.
$$
The <ratio test> proves \b[the series converges]. Its zero term at $n=0$ has no effect.