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A219239
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Double magic numbers (in physics).
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0
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4, 10, 16, 22, 28, 30, 36, 40, 48, 52, 56, 58, 70, 78, 84, 90, 100, 102, 110, 128, 132, 134, 146, 154, 164, 176, 208, 252
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OFFSET
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1,1
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COMMENTS
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For the magic numbers see A018226.
An atomic nucleus is called double magic if Z (number of protons in an atomic nucleus, atomic number) and N (number of neutrons) are both magic numbers. The nucleon or mass number (forget the Z electrons) is A = Z + N.
Each number a(n) is obtained in only one way as a sum of two (possibly equal) magic numbers. Only 28 is magic and double magic.
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LINKS
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Table of n, a(n) for n=1..28.
Wikipedia, Double magic.
Wikipedia, List of Nuclides.
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FORMULA
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a(n) is the sum of two numbers from [2, 8, 20, 28, 50, 82, 126] (the magic numbers A018226).
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EXAMPLE
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Tin-132 is a double magic radionuclide (unstable isotope) with nucleon number A = 132 = a(21), Z = 50 and N = 82. Similarly for tin-100 with Z = N = 50. The stable primordial nuclide barium-132 is not double magic, because it has Z = 56 and N = 76.
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CROSSREFS
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Cf. A018226, A033547.
Sequence in context: A310523 A310524 A140493 * A141427 A310525 A310526
Adjacent sequences: A219236 A219237 A219238 * A219240 A219241 A219242
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KEYWORD
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nonn,fini
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AUTHOR
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Wolfdieter Lang, Dec 12 2012
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STATUS
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approved
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