If the equation above is true for some positive integers , , and , with coprime, find .
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Starting with, S = n ≥ 1 ∑ n 2 ψ ( 1 ) ( n ) = n ≥ 1 ∑ n 2 ζ ( 2 ) − H n − 1 ( 2 ) = ζ 2 ( 2 ) − n ≥ 1 ∑ n 2 H n ( 2 ) − n 2 1 = ζ 2 ( 2 ) + ζ ( 4 ) − n ≥ 1 ∑ n 2 H n ( 2 )
Using the generalised harmonic summation , n = 1 ∑ ∞ n m H n ( m ) = 2 1 ( ζ 2 ( m ) + ζ ( 2 m ) ) for m ≥ 2
Using above we have, S = 2 1 ( ζ 2 ( 2 ) + ζ ( 4 ) ) = 3 6 0 7 π 4 = 4 7 ζ ( 4 )
Hence the answer : 7 + 4 + 4 = 1 5