Hydrogen: E_1 = -Z²/2; E_1/E_2 = 4; E_∞ = 0 (Rydberg ionisation limit)

Sympy-exact symbolic witness of the hydrogen-atom spectrum at three canonical anchors. Setup: E_n = -Z²/(2·n²) as a sympy expression with Z, n positive symbols. Canonical form: E_n_sym = '-Z**2/(2*n**2)' (sympy Mul-canonical with the…