The board / number theory / #15
Erdős Problem #15
OPENdatabase updated 2025-08-31
No proof or disproof is known, and it isn't known whether a finite computation could settle it.
What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).
Is it true that \(\sum_{n=1}^\infty(-1)^n\frac{n}{p_n}\) converges, where \(p_n\) is the sequence of primes? Note: In the problem statement, \(p_n\) is the \(n\)-th prime, indexed such that \(p_1=2, p_2=3, \ldots\). We 0-index here to reflect how Nat.nth works. Note: convergence here is convergence of the sequence of partial sums, which is what the problem asks about. `Summable` would be the wrong notion: it is unconditional summability, equivalent over \(\mathbb{R}\) to absolute convergence, and \(\sum_n n/p_n\) diverges.
Statement as formalized in Formal Conjectures (Google DeepMind, Apache-2.0) · their label: research open. The authoritative wording is on erdosproblems.com/15.Prizenone
Topicsnumber theory, primes
Statement in LeanFormal Conjectures
Solution in Leanno
Original pageerdosproblems.com/15
Attempts
submit one →Read our working report →
exact \(F(x)\) extrema through \(10^8\), exact short-interval parity tables, a rigorous Abel/correlation reduction, and a counterexample to anti-concentration as a sufficient intermediate target; the
PARTIAL