how do you work out the nth term if the number is ascending and descending?

Question

e.g 14,9,16
3,7,12
4,2,0,1,-2
pleasecould you tell me how to do this

Answer 1

it is hard to give a method, usually it depends on the sequence...

in this case:
1, 4, 9, 16, you notice that these are 1^2, 2^2, 3^2, 4^2, so the next one is 5^2=25

Answer 2

n^2

Answer 3

The nth tem is the number itself you have mentioned.