Problem 68

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Statement. Is

$$\sum_{n\geq 2}\frac{1}{n!-1}$$

irrational?

Status. Open.

Source. erdosproblems.com/68, accessed 2026-09-04. Cite as: T. F. Bloom, Erdős Problem #68, https://www.erdosproblems.com/68.

References.

• [Er88c] Erdős, P., On the irrationality of certain series: problems and results. New advances in transcendence theory (Durham, 1986) (1988), 102-109.

Formalization. Statement in formal-conjectures.

Progress

Not yet compiled.

Known Results

Not yet compiled.

Linked library material

These entries are derived from explicit links on library pages. They are navigation only and do not by themselves record mathematical progress.

• erdos_1969_irrationality_certain_series
• erdos_1976_problems_results_irrationality_sum_infinite_series
• erdos_1976_problems_results_irrationality_sum_infinite_series / question_p2
• erdos_1988_irrationality_certain_series_problems_results
• kaneko_2026_refinements_erdos_s_irrationality_criterion_certain