∫ 0 1 1 + x 2 ( 1 − x ) ln ( 1 − x ) d x = − G + c a π b − g ( ln f ) d + j π ln h
The equation above holds true for positive integers a , b , c , d , f , g , h and j , with a , c coprime and both f , h minimized.
Find the value of a + b + c + d + f + g + h + j .
Notation : G denote Catalan's constant , G = n = 0 ∑ ∞ ( 2 n + 1 ) 2 ( − 1 ) n ≈ 0 . 9 1 6 .
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If we define F ( x ) = n ≥ 1 ∑ n H n x n = − ∫ 0 x u ( 1 − u ) ln ( 1 − u ) d u = 2 1 ln 2 ( 1 − x ) + L i 2 ( x ) for ∣ x ∣ < 1 , so that (by Abel's Lemma) F ( i ) = lim y → 1 − F ( y i ) = = 2 1 ln 2 ( 1 − i ) + L i 2 ( i ) = 2 1 [ 2 1 ln 2 − 4 1 π i ] 2 + i G − 4 8 1 π 2 8 1 ( ln 2 ) 2 − 9 6 5 π 2 + i ( G − 8 1 π ln 2 ) then since ∫ 0 1 x 2 n ( 1 − x ) ln ( 1 − x ) d x = = = m ≥ 1 ∑ m 1 ∫ 0 1 x 2 n + m ( x − 1 ) d x m ≥ 1 ∑ ( m ( m + 2 n + 2 ) 1 − m ( m + 2 n + 1 ) 1 ) 2 n + 2 H 2 n + 2 − 2 n + 1 H 2 n + 1 for all n ≥ 0 , we see that ∫ 0 1 1 + x 2 ( 1 − x ) ln ( 1 − x ) d x = = = = n ≥ 0 ∑ ( − 1 ) n ( 2 n + 2 H 2 n + 2 − 2 n + 1 H 2 n + 1 ) − n ≥ 0 ∑ 2 n + 2 H 2 n + 2 i 2 n + 2 + i n ≥ 0 ∑ 2 n + 1 H 2 n + 1 i 2 n + 1 − R e [ F ( i ) ] − I m [ F ( i ) ] − G + 9 6 5 π 2 − 8 1 ( ln 2 ) 2 + 8 1 π ln 2 making the answer 5 + 2 + 9 6 + 2 + 2 + 8 + 2 + 8 = 1 2 5 .