Is there an easy way to define steps in a range in Calc?

[LesterK]

What I want is AVERAGE(B2, B9, B16, B23 … B989, B996).
I tried it this way: AVERAGE(B2:7:B1000).
The result was a Err:502.
Is there an easy way to only get every seventh value?

[LesterK]

I have a Solution:

=SUMPRODUCT(B2:B1000,MOD(ROW(B2:B1000),7)=2)/SUMPRODUCT(MOD(ROW(B2:B1000),7)=2)

But I am interested if there is a better one.