Product under Summation (Part 4)

Calculus Level 5

S = 1 + 9 ( 1 4 ) 4 + 17 ( 1 5 4 8 ) 4 + 25 ( 1 5 9 4 8 12 ) 4 + = 1 + r = 1 [ ( 8 r + 1 ) k = 1 r ( 4 k 3 4 k ) 4 ] \begin{aligned} S &=& 1 + 9\left(\dfrac{1}{4}\right)^4 + 17\left(\dfrac{1\cdot 5}{4\cdot 8}\right)^4 + 25\left(\dfrac{1\cdot 5\cdot 9}{4\cdot 8\cdot 12}\right)^4 + \ldots \\ &=& 1 + \sum_{r=1}^{\infty} \left[ (8r+1) \prod_{k=1}^{r} \left(\dfrac{4k-3}{4k}\right)^4 \right] \end{aligned}

Given that S S can be represented as A 3 2 π B C Γ 2 ( D E ) \dfrac{A^{\frac{3}{2}} \pi^{-\frac{B}{C}}}{\Gamma^2\left(\dfrac{D}{E}\right)} where A , B , C , D A,B,C,D and E E are positive integers with gcd ( B , C ) = gcd ( D , E ) = 1 \gcd (B,C) = \gcd(D,E) = 1 .

Evaluate A + B + C + D + E A+B+C+D+E


See Also : Part 1 , Part 2 , Part 3


The answer is 12.

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1 solution

Tanishq Varshney
Jan 29, 2016

hey @Ishan Singh do you have its proof, I saw this here

Hint

Ishan Singh - 5 years, 4 months ago

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