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Erdős problem 1003

Are there infinitely many solutions to ϕ(n)=ϕ(n+1)\phi(n) = \phi(n+1), where ϕ\phi is the Euler totient function?

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FormalConjectures/ErdosProblems/

1003.lean

Retained formal statement3 of 3

Erdős [Er85e] says that, presumably, for every k1k \geq 1 the equation ϕ(n)=ϕ(n+1)==ϕ(n+k)\phi(n) = \phi(n+1) = \cdots = \phi (n+k) has infinitely many solutions.

[Er85e] Erdős, P., _Some problems and results in number theory_. Number theory and combinatorics. Japan 1984 (Tokyo, Okayama and Kyoto, 1984) (1985), 65-87.

FormalConjectures/ErdosProblems/1003.leanErdos1003.erdos_1003.variants.Icc1 lineExact file
True ↔ ∀ k ≥ 1, {n | ∀ iSet.Icc 1 k, n.totient = (n + i).totient}.Infinite
OpenStatement only, no proof

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