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A121291
Rounded partial sum of atomic weights of first n elements.
1
1, 5, 12, 21, 31, 43, 57, 73, 92, 112, 135, 160, 187, 215, 246, 278, 318, 353, 392, 432, 477, 525, 576, 628, 683, 739, 798, 857, 920, 986, 1055, 1128, 1203
OFFSET
1,2
EXAMPLE
a(1) = round(1.0080) = 1 = mean atomic weight of hydrogen (protium + deuterium + tritium).
a(2) = round (1.0080+4.003) = round(5.011) = 5 (heium 4 and rarer helium 3).
CROSSREFS
Sequence in context: A063559 A259913 A224824 * A272012 A272451 A097984
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Aug 24 2006
STATUS
approved