I cannot reproduce your equality in Mathematica: your rhs is about 49, see code: N[(-Zeta'''[1/2]/Abs[Zeta[1/2]] - 3 Zeta''[1/2] Zeta'[1/2]/Abs[Zeta[1/2]]^2 - 2 Zeta'[1/2]^3 Abs[Zeta[1/2]]^3 - Pi^3/4)/7, 30] – Per Alexandersson 2 days ago

@Per I don't have Mathematica. Is it possible you are working with low precision? This Wolfram Alpha query returns error 10^(-15): wolframalpha.com/input/…*z_2*z_1%2Fz_12^2+-2*z_1^3%2Fz_12^3+-+pi^3+%2F+%284%29%29%2F7%29%2Cz_3%3DRiemannZeta%27%27%27[1%2F2.0]%2Cz_2%3DRiemannZeta%27%27[1%2F2.0]%2Cz_1%3DRiemannZeta%27[1%2F2.0]%2Cz_12%3DAbs%28RiemannZeta%281%2F2.0%29%29 – joro 2 days ago

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@Per: you are missing a / in the second to last term. – Jack Huizenga 2 days ago

@Jack: Thanks! – Per Alexandersson 2 days ago

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