OFFSET
1,36
COMMENTS
Radioactive nuclides with a half-life of 700 million years or greater (i.e., half-life longer than or equal to that of uranium-235) are included.
The last known term is a(294) = 0, although there is still an unconfirmed nuclide, oganesson-295.
Sum_{n=1..294} a(n) = 286, which is the number of known stable nuclides.
For n <= 209, a(n) = 0 only for n = 5, 8, while for n > 209, a(n) != 0 only for n = 232, 235 and 238 (thorium-232, uranium-235 and uranium-238).
The total number of stable nuclides with an even mass number is 176, while for odd mass number it's 110. Among all 176 even-mass-number stable nuclides, only 9 of them are with an odd number of protons and neutrons: hydrogen-2, lithium-6, boron-10, nitrogen-14, potassium-40, vanadium-50, lanthanum-138, lutetium-176 and tantalum-180.
There are 43 even numbers k such that a(k) = 1, 53 such that a(k) = 2 and 9 such that a(k) = 3. There are 100 odd numbers such that a(k) = 1 and only 5 such that a(k) = 2 (rubidium-87/strontium-87, cadmium-113/indium-113, indium-115/tin-115, antimony-123/tellerium-123, rhenium-187/osmium-187).
LINKS
Jianing Song, Table of n, a(n) for n = 1..294
Jianing Song, Stable nuclides with mass number n
Wikipedia, Table of nuclides.
Wikipedia, Isobar.
EXAMPLE
Stable nuclides with mass number n:
n = 36: sulfur-36, argon-36;
n = 40: argon-40, potassium-40, calcium-40;
n = 124: tin-124, tellurium-124, xenon-124.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Sep 07 2018
STATUS
approved