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Search: id:A121818
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| A121818 |
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Average of atomic weights of all isotopes of first n elements, rounded to nearest integer. |
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+0
1
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| 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 38, 39, 40, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 60, 61, 62, 63, 65, 66, 67, 69, 70, 71, 72, 74, 75, 76, 78, 79, 80, 81, 83, 84, 85
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This is poorly defined, even with the caveats of A007656, for the highest atomic numbers (with no stable isotopes) and the values given are with respect to Earth, as different planets presumably have slightly different isotopic ratios.
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EXAMPLE
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a(1) = round(1.0080/1) = 1 = mean atomic weight of hydrogen (protium + deuterium + tritium).
a(2) = round((1.0080+4.003)/2) = round(5.011/2) = round(2.5055) = 3.
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MATHEMATICA
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(* first do *) Needs["Miscellaneous`ChemicalElements`"] (* then *) Table[ Round[ Sum[ AtomicWeight(AT)Elements[[i]], {i, n}]/n], {n, 111}] (* Robert G. Wilson v *)
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CROSSREFS
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Cf. A007656, A070217, A121291.
Sequence in context: A062983 A081311 A053233 this_sequence A026505 A029674 A132147
Adjacent sequences: A121815 A121816 A121817 this_sequence A121819 A121820 A121821
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KEYWORD
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nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Aug 26 2006
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EXTENSIONS
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More terms from Robert G. Wilson v, Sep 02 2006
Edited by N. J. A. Sloane (njas(AT)research.att.com), Sep 14 2006
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