4 ->2
5 ->2
6 ->2
8 ->4
9 ->4
10->4
12->6
13->6
14->6 ....
then let k be (2,3,4,6,...) and n be (4,5,6,8,9,10,12,13,14...)
then I have
$2k≤n≤2k+2$
$2k-1≤n-1≤2k+1$
$k-1/2≤(n-1)/2≤k+1/2$
$k≤(n-1)/2+1/2≤k+1$
but I cannot apply floor function or ceiling function.
If I have that
$2k≤n<2k+3$
$2k-3/2≤n-3/2<2k+3/2$
$k-3/4≤n/2-3/4<k+3/4$
$k≤n/2<k+3/2$
but I still cannot apply floor function or ceiling function.
Doesn't the formula exist?
$$n\le2k\lt n+4$$
$$\dfrac n4\le \dfrac k2\lt \dfrac n4+1$$
$$\dfrac k2=\left\lfloor \dfrac n4 \right\rfloor$$
$$k=2\left\lfloor \dfrac n4\right\rfloor$$