Answer
$2,1,0,1$
Work Step by Step
$a_n = 1+ sin(\frac{\pi n}{2})$
To find the first four terms, we need to find $a_1, a_2, a_3$, and $a_4$.
$a_1 = 1+ sin(\frac{\pi (1)}{2}) = 2$
$a_2 = 1+ sin(\frac{\pi 2}{2}) = 1$
$a_3 = 1+ sin(\frac{\pi 3}{2}) = 0$
$a_4 = 1+ sin(\frac{\pi 4}{2}) = 1$
