Does the series ∑n=1∞n2n4+1\sum_{n=1}^{\infty} \frac{n^2}{n^4+1}∑n=1∞n4+1n2 converge?
Yes, by comparison with ∑1n2\sum \frac{1}{n^2}∑n21
No, by comparison with ∑1n\sum \frac{1}{n}∑n1
Yes, by ratio test
Inconclusive