What version of Excel do you have? I suspect you don't have MS 365 and hence don't have the function SEQUENCE. An easy way to test is to start typing the equation =SE... and you should see a list of potential functions and if when you get to =SEQ that list is blank/goes away that means your version of Excel doesn't have that function/ability. BTW in that case just use Sergei's solution as that should work just fine.