Context
In the remaining f=2 split, one inner sum contributes both factors of two. Its odd part cycles through four residues modulo 24, leaving eight placements after the quadratic-reciprocity gate.
Proof or evidence
Canonical parity reduces possible lowest-digit cancellation to ten families. Complete mod-7 and mod-73 periods eliminate nine; the last residue class has 343 survivors modulo 487 and four modulo 2593, with no CRT-compatible pair.
Verification notes
Independent Python and C++ implementations reconstruct every survivor count and the terminal CRT incompatibility. A bounded census checks 870,168 canonical presentations, finds six controls, and finds no valuation-law failure; it is not used for completeness.
Limitations
- The theorem controls but does not exclude all complementary f=2 split-(2,0) solutions.
- The controlled f=1 branch, the f=0 rows, and arbitrary expression trees remain open.
- No external review or novelty determination is recorded.