For natural number n, define f_n(x) as the product cos(x) * cos(2x) * cos(3x) * .... * cos(nx).

What is the smallest n such that |f_n''(0)| > 2024?

So far every solution posted that has explained their answer has used a computer assist.  I would have hoped that someone put together an analytic solution without a computer.

Posted by Brian Smith on 2024-02-28 10:58:17