This record provides the preprint "Lehmer’s Totient Problem and a Prime-Cost Pivot Method". It resolves Lehmer’s totient problem by proving that no composite integer n satisfies phi(n) | (n − 1). The proof combines a prime-cost pivot inequality ruling out the large-parameter regime with a finite-range, machine-checkable certificate for the remaining window, verified by deterministic scripts. Companion materials (code and certificate artefacts) are provided in the associated companion repository for this record.
Daniel Sautot (Sun,) studied this question.