

A368859


Number of betastable isotopes of the nth element.


7



2, 3, 2, 2, 2, 2, 2, 3, 1, 3, 1, 3, 1, 3, 1, 4, 2, 3, 2, 5, 1, 5, 1, 4, 1, 4, 1, 5, 2, 5, 2, 5, 1, 6, 2, 6, 1, 4, 1, 4, 1, 7, 0, 7, 1, 6, 2, 7, 1, 10, 2, 7, 1, 9, 1, 7, 1, 4, 1, 7, 0, 8, 2, 8, 1, 8, 1, 6, 1, 7, 1, 6, 1, 5, 1, 7, 2, 6, 1, 7, 2, 4, 1, 6, 1, 6, 1, 7, 1, 7, 1, 7, 1, 6, 2, 5, 1
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OFFSET

1,1


COMMENTS

A betastable nuclide is a nuclide whose beta decay (betaminus and betaplus 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 (in the case of 48Ca, 96Zr, 123Te, 148Gd, 180mTa, 222Rn and 247Cm), is not classified as being betastable.
We know 7 betastable isotopes of californium (248252, 254, 256) and fermium (252, 254, 256260) respectively, but the unobserved nuclides 258Cf and 262Fm could be betastable as well.
Different from A179301: for Z <= 83, 5He, 8Be, 146Sm, 150Gd and 154Dy are betastable but not primordial. 40K, 48Ca, 50V, 96Zr, 113Cd, 115In, 123Te, 138La, 176Lu, 187Re and 180mTa are primordial but not betastable.
Page 12 of the Zagrebaev et al. link predicts that a(113) = 0.
Prediction of a(98)a(118) from a Russian source: 7, 1, 7, 1, 7, 1, 7, (1, 6 or 2, 5), 1, 4, 1, 7, 1, 7, 1, 7, 1, 7, 1, 7.
Prediction of a(98)a(125) from pages 1415 of the Hiroyuki Koura link: 8, 1, 8, 2, 8, 1, 10, 1, 9, 1, 10, 1, 9, 1, 6, 2, 10, 1, 10, 2, 13, 1, 9, 1, 9, 1, 9, 1.


LINKS



EXAMPLE

a(2) = 3 because helium3, 4 and 5 are betastable, even if helium5 has an extremely short halflife.
a(4) = 2 because beryllium8 and 9 are betastable, even if beryllium8 has an extremely short halflife.
a(62) = 8 because the betastable isotopes of samarium are of mass numbers 144, 146150, 152 and 154, with 146Sm being not primordial.
a(64) = 8 because the betastable isotopes of gadolinium are of mass numbers 150, 152, 154158 and 160, with 150Gd being not primordial.
a(66) = 8 because the betastable isotopes of samarium are of mass numbers 154, 156, 158, 160164, with 154Dy being not primordial.
a(84) = 6 because the betastable isotopes of polonium are of mass numbers 210214 and 216.


CROSSREFS



KEYWORD

nonn,fini,hard


AUTHOR



STATUS

approved



