 oxygen isotopes deduced from one-proton separation energies and the excitation energies of the lowest 0/0^−^ states in the odd--even nitrogen isotopes. The dotted bars indicate the adopted values for the observed excited states in ^00,00^N, which have been tentatively assigned as 0/0^−[@CR00]^. Other experimental data are taken from refs. ^[@CR00],[@CR00],[@CR00]^. 