『フーリエの方法』
https://gyazo.com/f940f3ba274efa3c29444bd8ecedd26e
内田老鶴圃/書籍詳細/フーリエの方法
Divide%5Bpi%2C4%5D%2BSum%5B(Divide%5B1%2CPower%5Bm%2C2%5Dpi%5D(Power%5B(-1)%2Cm%5D-1)cosmx-Divide%5B1%2Cm%5DPower%5B(-1)%2Cm%5Dsinmx)%2C{m%2C1%2Cinf}%5D - Wolfram|Alpha