Information on mass chains and nuclides available on this website:

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²⁰Mg has not been observed [see, however, (MA64CC)]. The mass excess of ²⁰Mg is calculated to be 17.509 ± 0.002 MeV (using the senority scheme) and 17.510 ± 0.002 MeV (using the supermultiplet scheme). ²⁰Mg would then be stable with respect to breakup into ¹⁹Na + p by 2.75 MeV (HA69H). See also (GO62N, GA64A, GO64J, GO66J, GO66L, KE66C).