If the equation above holds true for positive integers and , with coprime, find .
Notations :
denotes the Catalan's constant , .
denotes the Riemann zeta function .
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Let I = ∫ 0 2 π x 2 csc x d x
Applying IBP ,
I = − 2 ∫ 0 2 π x ln ∣ c o s e c x − c o t x ∣ d x = ∫ 0 2 π − 2 x [ ln ( 2 sin 2 2 x ) − ln ( s i n x ) ] d x
Splitting into parts we get ,
I = − 2 ∫ 0 2 π x ln ( 2 sin 2 2 x ) d x + 2 ∫ 0 2 π x ln ( sin x ) d x
Both the integrals can be calculated separately and I have done that in previous cases so I'm skipping the part,
Consider a function F ( a , b ) = ∫ 0 2 π sin a x cos b x d x = Γ ( 2 a + b + 2 ) Γ ( 2 a − b + 2 ) 2 − a Γ ( a + 1 ) π cos ( 2 b π )
We can calculate ∂ a ∂ b ∂ 2 F ( 1 , 1 ) which equals our integrals .
After calculation , { 2 ∫ 0 2 π x ln ( 2 sin 2 2 x ) d x = − 2 π G + 8 3 5 ζ ( 3 ) − 4 π 2 ln 2 2 ∫ 0 2 π x ln ( sin x ) d x = 8 7 ζ ( 3 ) − 4 π 2 ln 2
So I = 2 π G − 2 7 ζ ( 3 ) , Thus answer is 2 + 7 + 2 + 3 = 1 4