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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..33.

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

Cf. A007656, A070217.

Sequence in context: A063559 A259913 A224824 * A272012 A272451 A097984

Adjacent sequences:  A121288 A121289 A121290 * A121292 A121293 A121294

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Aug 24 2006

STATUS

approved

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Last modified August 21 21:36 EDT 2017. Contains 290908 sequences.