

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
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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



KEYWORD

nonn,fini,less


AUTHOR



EXTENSIONS



STATUS

approved



