How do I interleave two lists or data in Google Spreadsheets?

Question

I want to combine two lists in Google Spreadsheet so that the cells interleave.
Both lists have the same amount of elements.

So that:

1          A
2          B
3          C

becomes:

1
A
2
B
3
C

The closest I came up with is something like JOIN({List A},{List B}), but in this way the Elements of List B are only split by the first Element of List A.

It would be great if someone has an idea without any add-ons using only the built-in functions. Transposing and formatting is not that important.

Answer 1

Try:

=ArrayFormula(transpose(split(concatenate(A1:B&char(9)),char(9))))

(note that concatenate has a limit of 50000 characters)

or

=transpose(split(join(" ",query(transpose(A1:B),,50000))," "))

Where list A starts in A1, list B in B1.