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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Statement

Notation (p. 11): r(p)r(p) is the least primitive root of the prime pp. The passage follows conjecture (4) and states, in this order, without proof:

  1. A proof of
∑p<xr(p)=(1+o(1)) c xlog⁡x\sum_{p<x}r(p)=\bigl(1+o(1)\bigr)\,c\,\frac{x}{\log x}

seems very hard. 2. It has not even been proved that r(p)r(p) does not tend to infinity with pp. 3. Artin conjectured that 22 is a primitive root of infinitely many primes, and a proof seems very hard. 4. As far as the author knows, it has not even been proved that every prime pp has a prime q<pq<p that is a primitive root of pp. In the paper's words: "Tudtommal még az sincs bebizonyítva, hogy minden pp prímszámhoz van oly q<pq<p prímszám, mely pp-nek primitív gyöke." 5. After reviewing upper bounds for r(p)r(p) (Vinogradov's (5), r(p)<p1/2+εr(p)<p^{1/2+\varepsilon} for p>p0(ε)p>p_0(\varepsilon); the improvement of Hua, H. Shapiro and the author to r(p)<c3p1/2v(p−1)c4r(p)<c_3p^{1/2}v(p-1)^{c_4}, with v(p−1)v(p-1) the number of distinct prime factors of p−1p-1; and a sharper power bound of Burgess and Wang), the paper says it may well be that r(p)<clog⁡pr(p)<c\log p.

Item 4 quantifies over every prime pp, as printed; for p=2p=2 there is no prime below pp.

Source. P. Erdős, Számelméleti megjegyzések, I. (Remarks on number theory, I.; in Hungarian), Mat. Lapok 12 (1961), 10--17; MR 26 #2410, Zbl 0154.294. All five remarks on printed p. 11, read on the page image of the edition identified on the source card. The exponent in the displayed Burgess--Wang bound is not legible on the scan and is not recorded here.

Read depth. Claims checked: the passage was read clause by clause on the page image. It contains no proofs.

Bears on

  • Problem 985: item 4 is the problem's question in the site's wording (every prime pp), which the problem page cites at p. 11; the problem page's corrected Statement asks it for every prime p>2p>2. The paper records it as not known and proves nothing about it.