The appendix of "Stefan Boltzmann law"

Japanese version
The special value of the Zeta function is important for the law of Planck, and the same thing is important also for the law (the energy distribution of black body radiation is proportional to the 4-th power of absolute temperature) of Boltzmann. From the formula of Planck, the law of Boltzmann can be drawn and it is in agreement with the observed value in experiments.

The Zeta function appears similarly in these derivation processes, this is indicated as the appendix of the article "Stefan Boltzmann law" in en.Wikipedia in English. Since there was no description of them in Japanese version, I translate it into Japanese.
The original article:
Stefan–Boltzmann law

a Japanese translation of the appendix of "Stefan-Boltzmann law":
The Appendix of "Stefan–Boltzmann law" (in Japanese)