There should be something wrong. Since I saw the time dependency from 't' I expect that you are speaking of an analog signal and 'n' is a parameter to be set. In this case you will have a period that is T=6/(2n-1) function of the parameter 'n' and this is also the fundamental period.
If instead you are speaking of a discrete sequence, 't' should not appear or have to be a costant, then you have to find the fundamental period as the smallest integer over which the sequence repeats.