> The summary description matches the current correct code. So it could not possibly match any incorrect code.

Incorrect. Here's the summary reproduced (in case susam edits again):

>>> There are 500 doors numbered 1, 2, ..., 500. All doors are closed initially. In iteration k, we toggle the states of doors k, 2k, ..., floor(500/k) * k where k runs from 1 to 500

Note the "floor(500/k)" statement. That matched the original code fragment (and what is still sitting in a terminal on my laptop):

    >>> [k**2 for k in range(1, int(500**0.5))]

but not the new one which includes a +1. int(…) is floor. int(…)+1 isn't, and it's wrong: It works for 500, but not for other values. math.ceil would have been more correct, but it might've been more obvious that it doesn't match the "summary".

> (if it really existed).

Let me make sure I understand what you mean here: You actually think it more likely that my two implementations, written in a comment [1] with a lower timestamp than [2], and the perl6 implementation on the linked article all include 484 as part of the valid result, and yet my comment [2] that calls on this value specifically, was somehow meant to indicate that 484 is not part of the valid result?

Ha.

[1]: https://news.ycombinator.com/item?id=22288534

[2]: https://news.ycombinator.com/item?id=22288554