Erdős problem 267
If with , must be irrational? The proposed proof closes the range left open by earlier criteria.
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If $n_1 < n_2 < \cdots$ with $n_{k+1}/n_k \ge c > 1$, must $\sum_k 1/F_{n_k}$ be irrational? The proposed proof closes the range $1 < c < 2$ left open by earlier criteria.
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