I think
@quagma would be Schrodinger's cat in this case, while the nth chair is/are the undefined values in the infinite sequence that is beyond the chairs that have already been filled.
As a side tangent, as a query directed towards Quagma, presumably the sequence is only composed of natural numbers, no? Given that Quagma has only been referenced in whole number terms, and has not existed as any of the other real numbers not within the category of whole or natural. Nor has the number of Quagmas been expressed as any of the complex numbers.