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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 Table of n, a(n) for n=1..72. 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 Cf. A007656, A070217, A121291. Sequence in context: A081311 A366935 A053233 * A179005 A026505 A029674 Adjacent sequences: A121815 A121816 A121817 * A121819 A121820 A121821 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.)