Answer
The given sequence is arithmetic sequence and the common difference = 1.
Work Step by Step
The given general term is $a_{n}$ = n - 3
First term $a_{1}$ = -2 (if n=1)
Second term $a_{2}$ = -1 (if n=2)
Third term $a_{3}$ = 0 (if n=3)
Forth term $a_{4}$ = 1 (if n=4)
Difference of consecutive terms.
1 - 0 = 1.
0 - (-1) = 1.
(-1) - (-2) = 1.
From above we observe that the difference between two consecutive terms is constant. So the given sequence is arithmetic sequence and the common difference = 1.