Consider sequence $s(n) = sin{nx}$. Are there values of $x$ for which the following holds: For every $y in [-1,1]$ there is a subsequence of $s(n)$ converging to $y$? (Or perhaps just for the open interval...) Someone hypothesised that the answer is yes, and further that every $x$ that is relatively irrational with $pi $ has this property.
The question I am more interested in is the generalised version of this to arbitrary sequences. What are necessary and sufficient conditions for a sequence having subsequences converging to any point in the set of values the sequence visits? Does it have anything to do with properties like the function $f(n)$ being ergodic or mixing?
(suggestions for tags welcome in comments)
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