Single Column -> Multiple Rows

I have a single column of about 1500 points, and I need them to be separated into many rows of 20 numbers.

I have multiple issues:

1) The middle number of each row (10th and 11th) need to be repeated. So a transpose formula can not work all the way through the 20 numbers. Unless I transpose the first ten, then tranpose the second ten. Is there an easier way around this ?

2) The bigger issue is, I would like to write a formula that can manipulate the date to enter in the correct cell.

To illustrate I will use a set of ten numbers:

1
2
3
4
5
6
7
8
9
10
11
12

INTO
1
2
3
4

5
6
7
8

9
10
11
12