number-theory / Analytic number theory; smooth numbers and largest prime factors

Erdos Problem #371: do the integers with P(n) < P(n+1) have density 1/2? (Erdos-Pomerance joint independence of largest prime factors)

Theorem 1.1: for fixed a,b∈(0,1)a,b\in(0,1), 1X#{2≤n≤X:P+(n)≤na,P+(n+1)≤nb}→ρ(1/a)ρ(1/b)\frac1X\#\{2\le n\le X:P^+(n)\le n^a,P^+(n+1)\le n^b\}\to\rho(1/a)\rho(1/b), unconditionally and at every large scale. Corollary 1.2: P+(n)<P+(n+1)P^+(n)<P^+(n+1) and the reverse ordering each have natural density 1/21/2. Inclusion-exclusion also gives the Erdos-Pomerance upper-tail independence statement. It gives no rate and no uniformity in a,ba,b (unlike the almost-all-scales quantitative law of Tao-Teravainen 2026), and says nothing about three consecutive integers (Erdos #372 and Balog's density 1/6 conjecture).

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number-theorySep 24, 2026Significance 30/100Registry: lean checked

Erdos Problem #371: do the integers with P(n) < P(n+1) have density 1/2? (Erdos-Pomerance joint independence of largest prime factors)

Prior state unknown→proved

Theorem 1.1: for fixed a,b∈(0,1)a,b\in(0,1), 1X#{2≤n≤X:P+(n)≤na,P+(n+1)≤nb}→ρ(1/a)ρ(1/b)\frac1X\#\{2\le n\le X:P^+(n)\le n^a,P^+(n+1)\le n^b\}\to\rho(1/a)\rho(1/b), unconditionally and at every large scale. Corollary 1.2: P+(n)<P+(n+1)P^+(n)<P^+(n+1) and the reverse ordering each have natural density 1/21/2. Inclusion-exclusion also gives the Erdos-Pomerance upper-tail independence statement. It gives no rate and no uniformity in a,ba,b (unlike the almost-all-scales quantitat…

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Theorem 1.1: for fixed a,b∈(0,1)a,b\in(0,1), 1X#{2≤n≤X:P+(n)≤na,P+(n+1)≤nb}→ρ(1/a)ρ(1/b)\frac1X\#\{2\le n\le X:P^+(n)\le n^a,P^+(n+1)\le n^b\}\to\rho(1/a)\rho(1/b), unconditionally and at every large scale. Corollary 1.2: P+(n)<P+(n+1)P^+(n)<P^+(n+1) and the reverse ordering each have natural density 1/21/2. Inclusion-exclusion also gives the Erdos-Pomerance upper-tail independence statement. It gives no rate and no uniformity in a,ba,b (unlike the almost-all-scales quantitative law of Tao-Teravainen 2026), and says nothing about three consecutive integers (Erdos #372 and Balog's density 1/6 conjecture).

Theorem 1.1: for fixed a,b∈(0,1)a,b\in(0,1), 1X#{2≤n≤X:P+(n)≤na,P+(n+1)≤nb}→ρ(1/a)ρ(1/b)\frac1X\#\{2\le n\le X:P^+(n)\le n^a,P^+(n+1)\le n^b\}\to\rho(1/a)\rho(1/b), unconditionally and at every large scale. Corollary 1.2: P+(n)<P+(n+1)P^+(n)<P^+(n+1) and the reverse ordering each have natural density 1/21/2. Inclusion-exclusion also gives the Erdos-Pomerance upper-tail independence statement. It gives no rate and no uniformity in a,ba,b (unlike the almost-all-scales quantitative law of Tao-Teravainen 2026), and says nothing about three consecutive integers (Erdos #372 and Balog's density 1/6 conjecture).

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