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Erdős problem 68

n=21n!1=n=2k=11(n!)k\sum_{n=2}^\infty \frac{1}{n!-1} = \sum_{n=2}^\infty \sum_{k=1}^\infty \frac{1}{(n!)^k}

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FormalConjectures/ErdosProblems/

68.lean

Retained formal statement1 of 2

Is n=21n!1\sum_{n=2}^\infty \frac{1}{n!-1} irrational?

FormalConjectures/ErdosProblems/68.leanErdos68.erdos_681 lineExact file
TrueIrrational (∑' (n : ℕ), 1 / (↑(n + 2).factorial - 1))
OpenStatement only, no proof

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