Аннотация:We find the asymptotics of the series $\sum_{n=1}^\infty (−1)^n/n \exp(−t/n)$ as $t\to+\infty$. The answer is an oscillating function of $t$ dominated by $exp(−(2\pi t)^{1/2})$. The intermediate step is to find the asymptotics of the two-dimensional Fourier transform $\hat F(\xi)$ of the function $F(x)=1/(1+\exp(\|x\|^2))$ as $\|\xi\|\to\infty$.