Glycan mass additivity: M(n) = 162n + 18; M(1)=180, M(2)=342, M(10)=1638

Sympy-exact witness of the glycan-mass residue-plus-terminal arithmetic. Setup: monomer mass 180, residue mass 162 (= 180 − 18 after water loss), M(n) = 162·n + 18 for n-hexose linear polymer. Pins: M_sym = '162*n + 18' (sympy canonical…