A121291 Rounded partial sum of atomic weights of first n elements.

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

Author

Jonathan Vos Post, Aug 24 2006

Keywords

• nonn

Examples

			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.