Theorem concerning analytic continuation

A. I. Markushevich obtained the following representation of a function in its holomorphicity star with a sequence $\{m_\nu\}$, for which $m_{\nu+1}/m_\nu\to\infty$:
$$f(z)=\lim\limits_{\nu\to\infty}\left\{\sum_0^{m_{2\nu}}\theta_k\frac{f^{(k)}(z_0)}{k!}(z-z_0)^k+\sum_0^{m_{2\nu-1}}(1-\theta_k)\frac{f^{(k)}(z_0)}{k!}(z-z_0)^k\right\}$$
. Here it is proved that this condition is necessary; more precisely, $\overline{\lim\limits_{\nu\to\infty}}\frac{m_{\nu+1}}{m_\nu}=\infty$ . This result is derived from certain properties of over-convergent power series.