Chapter 8, Sequences and Series - Section 8.1 - Sequences and Summation Notation - 8.1 Exercises - Page 600: 11

$a_{1}=0$ $a_{2}=2$ $a_{3}=0$ $a_{4}=2$ $a_{100}=2$

We are given: $a_{n}=1+(-1)^{n}$ We evaluate: $a_{1}=1+(-1)^{1}=1-1=0$ $a_{2}=1+(-1)^{2}=1+1=2$ $a_{3}=1+(-1)^{3}=1-1=0$ $a_{4}=1+(-1)^{4}=1+1=2$ $a_{100}=1+(-1)^{100}=1+1=2$