■ある無限級数(その119)
[1]πが出現する無限級数
1+1/2^2+1/3^2+1/4^2+・・・=π^2/6
1+1/2^4+1/3^4+1/4^4+・・・=π^4/90
1−1/2^2+1/3^2−1/4^2+・・・=π^2/12
1−1/2^4+1/3^4−1/4^4+・・・=7π^4/720
1−1/3^3+1/5^3−1/7^3+・・・=π^3/32
1−1/3^5+1/5^5−1/7^5+・・・=5π^5/1536
1+1/3^2+1/5^2+1/7^2+・・・=π^2/8
1+1/3^4+1/5^4+1/7^4+・・・=π^4/96
1/0.5^2+1/1.5^2+1/2.5^2+1/3.5^2+・・・=π^2/2
1/0.5^2+1/1^2+1/1.5^2+1/2^2+・・・=2π^2/3
[2]ゼータ関数が出現する無限級数
1/ζ(s)
=(1−1/2^2)(1−1/3^s)(1−1/5^2)(1−1/7^s)・・・
=Σμ(n)/n^s
=1−1/2^s−1/3^s−1/5^s+1/6^s−1/7^s+1/10^s−1/11^s−・・・
===================================
[参]若原龍彦「美しい無限級数」プレアデス出版
===================================