universal layer number is sizable for the layered conductivity while it is modest for the bunched conductivity. This feature may be used to test the validity of the layered conductivity.

This paper is composed as follows. Basic knowledge about transfer matrix method and electronic states of an $N$-layer graphene with AB stacking order is provided in Sec. \[sec:rev\]. We formulate those two dynamical conductivities in Sec. \[sec:for\] and show the calculated results in Sec. \[sec:cal\]. We conclude this paper in Sec. \[sec:con\]. We examine an $N$-layer graphene with AB stacking order in the main test. In Appendix \[app:largeN\], we show an analytic expression for the bunched dynamical conductivity of an $\infty$-layer graphene (or graphite) with AB stacking order. Some results for AA stacking are summarized in Appendix \[app:aa\].

Basic knowledge {#sec:rev}
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Transfer Matrix Method {#sec:tm}
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We explain the transfer matrix method in Fig. \[fig:sl\](c). [@Mizuno1994] The arrows along the $z$-axis indicate the propagation direction of light; the first graphene layer transmits and reflects the incident light in the forward and backward directions with certain amplitudes $c_1^t$ and $c_0^r$. Such transmission and reflection are repeated at each layer. The absolute square of $c_N^t$ and $c_0^r$ corresponds to the transmittance 