[R] weight in lm

[Troels Ring]

Dear friends - I hope you will accept a naive question on lm: R version 
3.4.1, Windows 10

I have 204 "baskets" of three types corresponding to factor F, each of 
size from 2 to 33 containing measurements, and need to know if the 
standard deviation on the measurements  in each basket,sdd, is different 
across types, F. Plotting the observed sdd  versus the sizes from 2 to 
33, called "k" , does show a decreasing spread as k increases towards 33.

I tried lm(sdd ~ F,weight=k) and got different results if omitting the 
weight argument but would it be the correct way to use sqrt(k) as weight 
instead?

Best wishes

Troels Ring
Aalborg, Denmark