Answer
$a_1=-1$
$a_2=-5$
$a_3=-9$
$a_4=-13$
Work Step by Step
$a_1=-1$
$a_2=a_1-4=-1-4=-5$
$a_3=a_2-4=-5-4=-9$
$a_4=a_3-4=-9-4=-13$
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