Let Si be a sequence in a set A.
Prove that Si has a constant subsequence iff there exists a in A such that for all n is in the natural numbers, there exists j≥n such that Si=a
Where I am confusing myself is with the j and the n. Is the n referring to the position of the subsequence in the original sequence?
I understand that a sequence does not need to be constant in order have a constant subsequence.
Where do i start?