The nth term can be anything you like! However, the simplest poynomial that fits these points is given by the rule:
Un = n2 + 2 for n = 1, 2, 3, ...
It is: 25-7n
7n - 3
Un = 25 - 7n
The nth term is 7n-3 and so the next term will be 39
If you mean: 15 11 7 3 then the nth term is 19-4n
It is: 25-7n
7n - 3
The nth term is: n^2 +2 and so the next number will be 38
Un = 25 - 7n
The nth term is 7n-3 and so the next term will be 39
The nth term in this sequence is 4n + 3.
The nth term is 18 -3n and so the next term will be 3
If you mean: 15 11 7 3 then the nth term is 19-4n
If you mean -1 3 7 11 15 then the nth term is 4n-5 and so the next term will be 19
Un = 5n - 2
It is: nth term = 5-4n and so the next term will be -19
The nth term is 4n-1 and so the next term will be 19