Create the problem statement for IMO 2025 #4#111
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a2435191 wants to merge 11 commits intodwrensha:mainfrom
Open
Create the problem statement for IMO 2025 #4#111a2435191 wants to merge 11 commits intodwrensha:mainfrom
a2435191 wants to merge 11 commits intodwrensha:mainfrom
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Author
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Sorry, I don't know why Github links |
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Author
dwrensha
reviewed
Nov 18, 2025
| def A₀ := { a₀ | ∃ a, a 0 = a₀ ∧ IsAllowed a } | ||
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| variable {x : ℕ+} | ||
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Owner
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Any of these items that are necessary for stating the problem should be hidden inside snip begin ... snip end, as descirbed here: https://github.com/dwrensha/compfiles?tab=readme-ov-file#extracting-problems
…add a link to the youtube proof
dwrensha
reviewed
Nov 22, 2025
| The infinite sequence a₁, a₂, ... consists of positive integers, each of which has at least three proper | ||
| divisors. For each n ≥ 1, the integer aₙ + 1 is the sum of the three largest proper divisors of aₙ. | ||
| Determine all possible values of a₁. | ||
| Proof follows https://www.youtube.com/watch?v=Kb4h_GVFT1k |
Owner
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Please put any comments about the proof either inside the snip begin ... snip end, or within in the tactic body of the problem proof, so that they don't show up as spoilers on the extracted problem webpage.
Author
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Done. I'll contribute more to the solution over the next few months
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Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Using https://www.youtube.com/watch?v=Kb4h_GVFT1k