Question

Rudin Problem 8.21

Answer 1

Let
\[L_{n} = \frac{1}{2\pi}\int_{-\pi}^{\pi}\lvert D_{n}(t) \rvert dt.\]

Answer 2

Prove that the sequence
\[\left\{L_{n} - \frac{4}{\pi^{2}}\log n\right\}\]
is bounded.