Skipping cells in Reference on new column

[aurelium]

Hi,

I want to able to do the following on Excel 2016:

A1 B1
A2 B2
A3 B3
A4 B4
A5 B5
A6

B1 = AVG (A1:A3)
B2 = AVG (A4:46)
B3 = AVG (A7:A9)

and so on....

What is the general formula I should enter in Cell B1 and drag down to be get that done?
Thanks.

 

[Tetra201]

Try this:

=AVG(OFFSET(B1,2*(ROW()-1),-1,3,1))