Is there some concise mathematical form to express the fact that a sequence repeats with period t beginning with the nth term? For example, the sequence {1,2,6,3,7,3,1,7,3,1,7,3,1,7,3,1,...} repeats with period 3 beginning with the 5th term. Can we say, for all n>4, if b=an then b=an+3?
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