Answer
$a_0=-1$
$a_1=1$
$a_2=0$
$a_3=1$
$a_4=1$
Work Step by Step
$a_0=-1$
$a_1=1$
$a_k=a_{k-2}+a_{k-1}$
$a_2=a_0+a_1=-1+1=0$
$a_3=a_1+a_2=1+0=1$
$a_4=a_2+a_3=0+1=1$
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