gh-35439: Fix doctests in oeis
Fixes #35437
### :books: Description
This branch fixes the doctests errors reported in #35437. However, this
solution is not robust to future changes in the oeis database.
### :memo: Checklist
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- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation accordingly.
### :hourglass: Dependencies
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URL: https://github.com/sagemath/sage/pull/35439
Reported by: David Coudert
Reviewer(s): Sébastien Labbé
