If you look at the sequence, you would observe:
5 - 2 = 3, 8 - 5 = 3, 11 - 8 = 3.
There is a common difference of 3, so the sequence is an Arithmetic Progression.
nth term of an AP = a + (n - 1)d
where a = 1st term = 2, d = common difference = 3
nth term of an AP = a + (n - 1)d
nth term of an AP = 2 + (n - 1)*3 = 2 + 3*n - 3*1 = 2 + 3n - 3
= 2 - 3 + 3n
= -1 + 3n
= 3n - 1
The nth term = 3n - 1, where n = 1, 2, 3, 4, 5,....
I hope this explains it.
