I want to sum 3 columns of every other row in Excel.

I know how to do the "sum every 3 columns" part:

```
=SUM(OFFSET($A40,0,3*(COLUMN(A40)-(COLUMN($A40)-1))-3,1,3))
```

How do I apply this formula so it sums every other row, starting with A40 ?

So A40, A42, A43 etc.

**Edit**:

Basically, if you look at this picture, I am looking for formula, that would allow to sum every red cell in N3 and then be copy-pasted to sum every yellow cell in O3.