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
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Aug 24 2006
STATUS
approved