Question Number 223254 by Tawa11 last updated on 19/Jul/25
$$\underset{\mathrm{n}\:\:=\:\:\mathrm{1}} {\overset{\infty} {\sum}}\left(−\:\:\mathrm{1}\right)^{\mathrm{n}\:\:+\:\:\mathrm{1}} \:\frac{\mathrm{H}_{\mathrm{n}} }{\mathrm{n}^{\mathrm{2}} } \\ $$