Auto fill / flash fill not working with formulas?

Good afternoon,
I have an excel with a large dataset, in which the relevant cells are every 6 rows: for example A1, A7, A13, and so on.
I would like to copy only the relevant cells to a new sheet, eliminating the non-relevant cells.
So A1 in Sheet1 should be copied to A1 in Sheet 2, A7 in Sheet1 should be copied to A2 in Sheet 2, A13 in Sheet1 should be copied to A3 in Sheet 2, and so on.
I entered in Sheet2 the first three formulas: in A1 I entered "=Sheet1!A1", in A2 I entered "=Sheet1!A7", in A3 I entered "=Sheet1!A13", and then tried auto fill and flash fill, but it does not work and does not find the pattern.
Flash fill does not work with formulas? Could you kindly help with a solution?
Thank you,
Mihai

Yes, filling works just fine with formulas.
But it doesn't recognize repeating patterns like that.
It will only incriment formulas by 1 row/column at a time.

Try

=INDEX(Sheet1!A:A,(ROWS($1:1)-1)*6+1)

Thanks Jonmo1,
I entered the formula "=INDEX(Sheet1!A:A,(ROWS($1:1)-1)*6+1)" in A1 in Sheet2 and it retrieves indeed A1 from Sheet1.
What should I do next in A2, A3, etc?
Mihai

Fill Down.

I did that and it returns "0" for all cells

Formula in A2 becomes "=INDEX(Report!A:A;(ROWS($1:2)-1)*6+1)" and the result is 0

Works for me

Works fine, thank you very much!

You're welcome.