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1194 of 1194 statement records

17 source collections · 43 mathematical fields

Source labels openErdős Problems · Number theory

Erdős Problem 412

Let σ1(n)=σ(n)σ_1(n)=σ(n), the sum of divisors function, and σk(n)=σ(σk1(n))σ_k(n) = σ(σ_{k-1}(n)). Is it true that, for every m,n2m, n ≥ 2, there exist some i,ji, j such that σi(m)=σj(n)σ_i(m) = σ_j(n)?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 413: I

Are there infinitely many barriers for ω?

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Source labels openErdős Problems · Number theory

Erdős Problem 413: Big Omega

Erdős believed there should be infinitely many barriers for Ω, the total prime multiplicity.

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Source labels openErdős Problems · Number theory

Erdős Problem 413: Ii

Does there exist some ε > 0 such that there are infinitely many ε-barriers for ω?

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Source labels openErdős Problems · Number theory

Erdős Problem 414

Let h1(n)=h(n)h_1(n) = h(n) and hk(n)=h(hk1(n))h_k(n) = h(h_{k-1}(n)). Is it true, for any m,nm,n, there exist ii and jj such that hi(m)=hj(n)h_i(m) = h_j(n)?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 416: I

Let V(x) count the number of n≤x such that ϕ(m)=n is solvable. Does V(2x)/V(x)→2 ?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 416: Ii

Let V(x) count the number of n≤x such that ϕ(m)=n is solvable. Is there an asymptotic formula for V(x)?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 417: I

LetV(x)=#{ϕ(m):1mx}V'(x)=\#\{\phi(m) : 1\leq m\leq x\}andV(x)=#{ϕ(m)x:1m}.V(x)=\#\{\phi(m) \leq x : 1\leq m\}. Does limV(x)/V(x)\lim V(x)/V'(x) exist?

Formalization note: We formalize the limit of the inverse fraction V'(x)/V(x) to ensure the limit is finite (bounded between 0 and 1).

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 417: Ii

Is it >1>1?

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Source labels openErdős Problems · Number theory

Erdős Problem 418: Density

It is open whether the set of non-cototients has positive density.

Source checked Jul 26, 20261 pinned Lean statementInspect problem