ArXe Research · June 2026 · Diego Luis Tentor Internal Conceptual Note Companion to: arxe_technical_note_lanthanides.md Do not cite or distribute without authorization Abstract The formula KD = n − 4 for Kramers doublets in lanthanide ions was initially identified as an empirical pattern awaiting formal derivation from the BC algebra of T⁻³ and T². This note establishes that the derivation…