R 中的双（嵌套）FOR 循环

Question

I am trying to write a double For loop in R, but for the following code the output is not what I need

k<-4
n<-5


for (i in 1:n) 
 for (j in 1:k+1) 
  cat(i,j, "\n")

Output:

> for (i in 1:n) 
+  for (j in 1:k+1) 
+   cat(i,j, "\n")
1 2 
1 3 
1 4 
1 5 
2 2 
2 3 
2 4 
2 5 
3 2 
3 3 
3 4 
3 5 
4 2 
4 3 
4 4 
4 5 
5 2 
5 3 
5 4 
5 5 

Why does j start with 2?

Answer 1

The +1 after k is adding to j, try

for (j in 1:(k+1))

to force the addition to happen to k