Problem 363 (difficulty: 3/10)

Convergent or divergent?

\(\displaystyle a)\ \sum_{n=1}^{\infty} {1\over n(n+1)(n+2)}\qquad\qquad b)\ \sum_{n=1}^{\infty} {n^2\over (2+{1\over n})^n}\)

Give me another random problem!