The sequence is enough, you just keep going till your fractions (multiplied by 4) do not change 10^-5 any more. You do not need the actual value of pi.
As soon as 4 * 1/(2n+1) < 0.00001, then you can stop looping. The sequence is the algorithm.
As soon as 4 * 1/(2n+1) < 0.00001, then you can stop looping. The sequence is the algorithm.