Answer Happy

4. For each series, does it satisfy the assumption of Cauchy condensation theorem? If it does, use it to determine whether the series converges or diverges. (1) n=1∑∞​nn​2​ (2) n=3∑∞​nlnn2​ (3) n=1∑∞​n2cos26nπ​​ (4) n=4∑∞​n(lnn)51​