Say we have a periodic sequencs, ABCDABCDABCDA... etc. We would normally call A term 1, B term 2, C term 3, etc. However, to find the nth term, do we need to designate A as term 0, B as term 1, etc? Since we would use n mod 4 to find the nth term, wouldn't this mean that 4, 8, 12, etc would have to correspond to 0 rather than 1, this showing that we have to start the sequence ordering from 0 rather than 1? Wouldn't this be in contrast to other sequences such as geometric and arithmetic that start at 1 rather than 0?