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A318998
Number of stable nuclides with neutron number n.
4
1, 2, 1, 1, 1, 2, 2, 2, 2, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 0, 5, 1, 3, 1, 3, 1, 3, 2, 5, 1, 4, 1, 3, 1, 3, 0, 3, 1, 3, 0, 4, 1, 4, 1, 4, 0, 4, 1, 4, 1, 6, 1, 4, 1, 3, 2, 4, 1, 5, 1, 4, 0, 4, 1, 4, 2, 3, 1, 3, 1, 4, 1, 4, 1, 5, 1, 3, 1, 5, 1, 3, 2, 7, 1, 2, 2, 2
OFFSET
0,2
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(177) = 0.
Sum_{n=0..177} a(n) = 286, which is the number of known stable nuclides.
For n <= 126, a(n) = 0 for n = 19, 35, 39, 45, 61, 89, 115, 123.
The total number of stable nuclides with an even neutron number is 220, while for odd neutron number it's 66.
The number of even numbers k such that a(k) = 1, 2, 3, 4, 5, 6, 7 are 5, 6, 28, 19, 6, 1, 1. There are 46 odd numbers such that a(k) = 1 and only 10 such that a(k) = 2.
LINKS
Wikipedia, Table of nuclides.
Wikipedia, Neutron number.
Wikipedia, Isotone.
EXAMPLE
Stable nuclides with neutron number n:
n = 20: sulfur-36, chlorine-37, argon-38, potassium-39, calcium-40;
n = 50: krypton-86, rubidium-87, strontium-88, yttrium-89, zirconium-90, molybdenum-92;
n = 85: neodymium-145, samarium-147.
CROSSREFS
Cf. A179301 (proton number), A318997 (mass number), A318999 (neutron excess).
Sequence in context: A273190 A086288 A104360 * A079951 A095407 A038605
KEYWORD
nonn
AUTHOR
Jianing Song, Sep 07 2018
STATUS
approved