Sequence generation in a table

The biggest constraint for me is here as an example I have taken only three cases i.e. c(257, 520, 110), however in reality I will be dealing with no of cases and that number is unknown. But your code will certainly generate me the required numbers. In above case for doing further calculations, I can define say

yy1 = as.numeric(yy[[1]])
yy2 = as.numeric(yy[2]])
yy3 = as.numeric(yy[[3]])

mean(yy[[1]])

mean(yy1)