How to calculate how many times a function inside a for loop inside a while loop will be called?

Question

I'm studying for my exams and a came through this exercise but I can't prove the result I found.

Given this piece of code:

int k = 0;
while (k < n/2) {
    for (int l=k+1; l<=n; l=l*2) {
        printf("\n");
    }
    k = k+2;
}

I am asked to calculate how many times printf() will be called.

I calculated by hand how many times it would be called for different values of n and found the following:

for n=2: it was called 2 times
n= 4:   3 times
n= 8:   6 times
n=16:  12 times
n=32:  24 times
n=64:  48 times

It seems to me like the function that would accept n as a parameter and return how many times printf() would run is:

f(n) = round((3/4)*n)

Is this the correct way to calculate how many times printf() will run based on the value of n or am I doing something wrong? Additionally what would be the correct way to justify my answer of how I calculated how many times it'll be called?

P.S. I've also calculated the O() complexity of the code above if that helps in any way.