Jurie, even if you didn't get the Tn shenanigans, you could still have looked for a pattern in the equations.
Example:
For T1, you notice that it is 2/5, and for T2, the denominator increases by 2.
The right side of the equation has a number that has a denominator that multiples the left side of the equation's denominator to get the very end term.
2/5 = 1/3 + 1/15.
The 5 * 3 = 15.
This pattern will continue forever.
You could also generalize this with a variable just like how Alan and melody described it.
The best idea to work with these is to get more practice.