Hi Juriemagic,
That is good except I am not sure about this bit.
From this we see that: 2a=2, therefore, a=1
3a+b = 3, therefore "b" calculates to 0
and a+b+c=T1=5, so "c" calculates to 4
Where did you get 2a=2 from?
I did that subtraction twice and then had all the numbers the same
(all 2 in this case, but the 2 is not relevent, it is that they are all the same on the second subtraction that is relevant)
So I knew I could express this a polynomial of degree 2.
After that I just looked at n^2 that is 1, 4, 9, 16
and compared it to the sequences 5, 8, 13, 20
and I could just see that I had to add 4. Denominator = n^2+4
[what you did might be right, but I don't understand it. ]