Chapter 11 - Sequences; Induction; the Binomial Theorem - Section 11.1 Sequences - 11.1 Assess Your Understanding - Page 827: 28

$\{a_n\}=\dfrac{1}{n(n+1)}$ .

We notice from the sequence that the numerator is constant at $1$. The denominator shows the pattern of $1*2$, $2*3$, $3*4$, etc. Thus, in general the denominator has the pattern of $n(n+1)$. So, we determine the sequence pattern as $$\{a_n\}=\dfrac{1}{n(n+1)}$$