Question

Find the number pattern

1,2,1,1,2,3,2,1,1,2,3,4,3, _, _, 1,2, _, _, _, _, _, 2

Answer 1

2,1
3,4,5,4,3

Answer 2

How though?

Answer 3

\[~~~~~~~~~~~~1,2,1\]\[~~~~~~~\;1,2,3,2,1\]\[~~~\;1,2,3,4,3,2,1\]\[1,2,3,4,5,4,3,2,1\]