English
The value of ζ at negative integers can be expressed via Bernoulli' numbers: ζ(-k) = −Bernoulli'(k+1)/(k+1).
Русский
Значение ζ(-k) выражается через Bernoulli': ζ(-k) = − Bernoulli'(k+1)/(k+1).
LaTeX
$$$$ \operatorname{riemannZeta}(-k) = -\frac{\mathrm{bernoulli}'(k+1)}{k+1}. $$$$
Lean4
theorem riemannZeta_four : riemannZeta 4 = π ^ 4 / 90 :=
by
convert congr_arg ((↑) : ℝ → ℂ) hasSum_zeta_four.tsum_eq
· rw [← Nat.cast_one, show (4 : ℂ) = (4 : ℕ) by simp, zeta_nat_eq_tsum_of_gt_one (by simp : 1 < 4)]
simp only [push_cast]
· norm_cast