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May 2026Number TheorySolved

A Complete Answer to Erdős Problem 690

Discovered by the Multiscalar Fields System

We prove that the natural density dk(p), of integers whose k-th smallest prime divisor is p, is not unimodal for every k ≥ 4, completing Erdős' classification. The proof was discovered by the Multiscalar Fields System with limited human interaction.

Read the full proof, with the paper, verifier code, and the problem statement alongside it.