A good opportunity to repost this: https://eprint.iacr.org/2025/1237.pdf
An opposite standpoint: Why it's so much harder to factor 21 on a quantum computer than 15: https://algassert.com/post/2500
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An opposite standpoint: Why it's so much harder to factor 21 on a quantum computer than 15: https://algassert.com/post/2500