If I have a formula to test if the dates meet a certain condition such as this:

=AND($A5>=DATE(2018,3,1),$A5<=DATE(2019,9,30))*1

How can I modify this to test the same time frame for years of specified intervals, such as every ten years or every 4 years??

I could just add in those years for the next 20 or 50 or 100 years, but I think there must be a better, more efficient, way, right?

Thank you!!