Talk:Idoneal number
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At most two more, or at most one more?
[edit]Several sites, including Wolfram Mathworld and OEIS A000926, state that there is at most one more idoneal number. The page here says at most two more. Which is correct? --Rpresser 17:02, 2 September 2021 (UTC)
- Two is correct, see Kani's paper. Unfortunately this is a widespread error appearing in multiple sources. Kani gives some speculation why related to the 1985 Frei paper, but I think it's mostly because there are 65 known fundamental imaginary quadratic discriminants with one class per genus and also 65 known even imaginary quadratic discriminants with this property (which appears to be a coincidence AFAIK). Weinberger proved that there's at most one more such fundamental discriminant and none under GRH, but idoneal numbers correspond to the even disriminants with this property, and I think some people simply confused the two. However I've removed the claim that the implication was only proved in the 2011 article, which seams dubious (the article itself doesn't seam to imply that). --GreenKeeper17 (talk) 18:11, 17 December 2021 (UTC)