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COMMENTS
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A beta-stable nuclide is a nuclide whose beta decay (beta-minus and beta-plus decay) is energetically disallowed; that is to say, a nuclide that has lower energy than its isobars with one more or one less proton. Note that double beta decay is allowed. A nuclide whose beta decay is energetially allowed, even if not observed, is not classified as being beta-stable. Therefore, there are no beta-stable isotones with neutron number 71 because tellurium-123 is not beta-stable.
An odd number N being a term means that there are no beta-stable isotones with neutron number N at all, and an even number N being a term implies that all beta-stable isotones with neutron number N are even-even nuclides.
Different models predict different continuations for this sequence: Page 12 of the Zagrebaev et al. link predicts 159, (165, 168, 171 or 165, 168, 172 or 165, 169, 172 or 166, 169, 172, assuming Lr and Mt each have a beta-stable isotopes and Sg, Bh and Hs each have at most two beta-stable isotopes of odd mass number), 176, 180, 182. A Russian source predicts 160, 164, 167 or 168, 174, 178, 182, 186. Pages 14-15 of the Hiroyuki Koura link predict 159, 162, 166, 170, 174, 178, 183, 188, 191, 194, 196, 200, 204, 208, 212, 215 (pages 14-15).
In contrast to many terms being known for this sequence, there are only four known atomic numbers with no beta-stable isotopes of odd mass number: 18, 43, 58 and 61. The Zagrebaev et al. link predicts that nihonium (atomic number 113) has no beta-stable isotopes.
N is a term if and only if there is an element with two beta-stable isotopes of odd mass number with respectively N-1 and N+1 neutrons. See the list of examples in A368856.
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