Making a for loop in r - r

Question

I am just getting started with R so I am sorry if I say things that dont make sense.
I am trying to make a for loop which does the following,
l_dtest[[1]]<-vector()
l_dtest[[2]]<-vector()
l_dtest[[3]]<-vector()
l_dtest[[4]]<-vector()
l_dtest[[5]]<-vector()
all the way up till any number which will be assigned as n. for example, if n was chosen to be 100 then it would repeat this all the way to > l_dtest[[100]]<-vector().
I have tried multiple different attempts at doing this and here is one of them.
n<-4
p<-(1:n)
l_dtest<-list()
for(i in p){
print((l_dtest[i]<-vector())<-i)
}
Again I am VERY new to R so I don't know what I am doing or what is wrong with this loop.
The detailed background for why I need to do this is that I need to write an R function that receives as input the size of the population "n", runs a simulation of the model below with that population size, and returns the number of generations it took to reach a MRCA (most recent common ancestor).
Here is the model,
We assume the population size is constant at n. Generations are discrete and non-overlapping. The genealogy is formed by this random process: in each
generation, each individual chooses two parents at random from the previous generation. The choices are made randomly and equally likely over the n possibilities and each individual chooses twice. All choices are made independently. Thus, for example, it is possible that, when an individual chooses his two parents, he chooses the same individual twice, so that in
fact he ends up with just one parent; this happens with probability 1/n.
I don't understand the specific step at the begining of this post or why I need to do it but my teacher said I do. I don't know if this helps but the next step is choosing parents for the first person and then combining the lists from the step I posted with a previous step. It looks like this,
sample(1:5, 2, replace=T)
#[1] 1 2
l_dtemp[[1]]<-union(l_dtemp[[1]], l_d[[1]]) #To my understanding, l_dtem[[1]] is now receiving the listdescandants from l_d[[1]] bcs the ladder chose l_dtemp[[1]] as first parent
l_dtemp[[2]]<-union(l_dtemp[[2]], l_d[[1]]) #Same as ^^ but for l_d[[1]]'s 2nd choice which is l_dtemp[[2]]
sample(1:5, 2, replace=T)
#[1] 1 3
l_dtemp[[1]]<-union(l_dtemp[[1]], l_d[[2]])
l_dtemp[[3]]<-union(l_dtemp[[3]], l_d[[2]])