4
4 - 3 = 1
1 - 3 = -2
-2 - 3 = -5
-5 - 3 = -8
It's the arithmetic sequence.
[tex]a_n=a_1+(n-1)d[/tex]
[tex]a_1=4,\ d=-3[/tex]
substitute
[tex]a_n=4+(n-1)(-3)=4-3n+3=-3n+7[/tex]
Answer: [tex]a_n=-3n+7[/tex]
