This is an arithmetic sequence.
The numbers differ by a constant.
The general form of an arithmetic sequence is:
[tex]a_n=a+(n-1)d[/tex]Where
a is first term
n is nth term
d is the common difference
Looking at the sequence, we can say the common difference is -3 [since 3 is subtracted from a term to get the next term]
Also, first term is 13
Now, we plug into formula:
[tex]\begin{gathered} a_n=a+(n-1)d \\ a_n=13+(n-1)(-3) \\ a_n=13-3n+3_{} \\ a_n=16-3n \end{gathered}[/tex]
