I am having trouble with this In - Out table... any hints or tips?

IN OUT
1 / 3
3 / 17
10 / 66
6 / 38

things get easier if you arrange the table in order of increasing In values:

1 3 6 10
3 17 38 66

differences:
2 3 4
14 21 28

Note that as the IN difference increases by 1, the OUT difference increases by a multiple of 7

OUT = 3 + 7(IN-1)