A recursive Buchstab switching improvement for the greatest prime factor of n^2+1

Source archive for the manuscript and verification code of a greatest-prime-factor weak form of Landau's fourth problem. The claimed theorem is P⁺(n²+1) > n^1.323 for infinitely many positive integers n, once the Grimmelt–Merikoski Type I/II estimates, the standard dimension-one linear sieve, and the finite Mellin–Perron transfer in the paper are granted.

The archive contains the TeX manuscript and rendered PDF, a Lean 4 project locked to toolchain v4.22.0 / Mathlib v4.22.0, a fixed-width C++ certificate, an arbitrary-precision Python audit, an exhaustive branch-coverage audit, and the analytic-transfer and source-version ledgers. The canonical grid is 1200 × 300 × 160; both numerical implementations print saving_lower=0.032303187971 and CERTIFIED=YES.

Verification code is licensed under GPL-2.0-only (LICENSE). The manuscript and project prose are CC BY 4.0 (LICENSE-PAPER.md). This deposit does not redistribute third-party PDFs recorded in the source-version ledger.