A318997 - OEIS

A318997

Number of stable nuclides with mass number n.

1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 2, 1, 3, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2

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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

Cf. A179301 (proton number), A318998 (neutron number), A318999 (neutron excess).