Σz^8n+1/(8n+1)=A+B+C+D
Σz^8n+3/(8n+3)=A-B-C+D
Σz^8n+5/(8n+5)=A-B+C-D
Σz^8n+7/(8n+7)=A+B-C-D
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一般に
Σz^mn+a/(mn+a)
=-1/m{ln(1-z)+(-1)^a(m even)ln(1+z)+f(z))
f(z)=Σcos2πna/m・ln(1-2zcos2πn/m+z^2)-2sin2πna/m・arctan(zsin(2πn/m)/(1-zcos)2πn/m))
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