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A121818 Average of atomic weights of all isotopes of first n elements, rounded to nearest integer. 2
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; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
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.
LINKS
EXAMPLE
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.
MATHEMATICA
Needs["Miscellaneous`ChemicalElements`"]
Table[ Round[ Sum[ AtomicWeight(AT)Elements[[i]], {i, n}]/n], {n, 111}] (* Robert G. Wilson v, Sep 02 2006 *)
CROSSREFS
Sequence in context: A081311 A366935 A053233 * A179005 A026505 A029674
KEYWORD
nonn,fini,less
AUTHOR
Jonathan Vos Post, Aug 26 2006
EXTENSIONS
More terms from Robert G. Wilson v, Sep 02 2006
Edited by N. J. A. Sloane, Sep 14 2006
STATUS
approved

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Last modified May 18 15:50 EDT 2024. Contains 372664 sequences. (Running on oeis4.)