Estimating the strong coupling from $\tau$ decay using accelerating series convergence

We apply the Euler transformation to accelerate the convergence of the QCD perturbative series with the aim to determine the strong coupling ${\alpha }_s$ in terms of the total $\tau$-decay rate $r_{\tau }$. The variation of the result with the order of the QCD perturbation theory is small and comparable with the uncertainties of $r_{\tau }$. We also present an estimate of a range of the yet unknown 5th and 6th order coefficients $k_5$ and $k_6$ of the Adler function.