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%I #27 Mar 16 2024 04:25:06
%S 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,
%T 28,30,31,32,33,34,35,36,38,39,40,41,43,44,45,46,47,49,50,51,52,53,55,
%U 56,57,58,60,61,62,63,65,66,67,69,70,71,72,74,75,76,78,79,80,81,83,84,85
%N Average of atomic weights of all isotopes of first n elements, rounded to nearest integer.
%C 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.
%e a(1) = round(1.0080/1) = 1 = mean atomic weight of hydrogen (protium + deuterium + tritium).
%e a(2) = round((1.0080+4.003)/2) = round(5.011/2) = round(2.5055) = 3.
%t Needs["Miscellaneous`ChemicalElements`"]
%t Table[ Round[ Sum[ AtomicWeight(AT)Elements[[i]], {i, n}]/n], {n, 111}] (* _Robert G. Wilson v_, Sep 02 2006 *)
%Y Cf. A007656, A070217, A121291.
%K nonn,fini,less
%O 1,2
%A _Jonathan Vos Post_, Aug 26 2006
%E More terms from _Robert G. Wilson v_, Sep 02 2006
%E Edited by _N. J. A. Sloane_, Sep 14 2006
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