Create lines from the index of a Python series or dataframe

Question

I created this dataframe:

x = [1,3,5,8,10,15,4,5,6,8,23,12,28]  
x = pd.DataFrame(x)

I created the following dataframe:

I created a new dataframe with the following code:

z = []
for i in range(len(x)):
    z.append(x[i:i+3])

And I got the following:

I would like to create a Dataframe where instead of the series go from the "i:i+3" would be something like "i:i==5", ie the final value would not be three forward indexes, but the value "5" of the column. I don’t know what code is used to get that list