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Erdős problem 946

There are infinitely many nn such that τ(n)=τ(n+1)τ(n) = τ(n+1). Proved in [He84]. Here τ is the divisor counting function, which is σ 0 in mathlib.

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FormalConjectures/ErdosProblems/

946.lean

Retained formal statement2 of 5

The number of nxn \le x with τ(n)=τ(n+1)τ(n) = τ(n+1) is at least x/(logx)7x / (\log x)^7 for all sufficiently large xx. Proved in [He84].

FormalConjectures/ErdosProblems/946.leanErdos946.erdos_946.variants.heathbrown_lower_bound1 lineExact file
(fun x => x / Real.log x ^ 7) =O[Filter.atTop] Erdos946.erdos946Count
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