Fill a column with dates for two days per week

Question

I need to keep track of an employee who works Mondays and Thursdays. I need to fill a column with dates for these days. I know how to do sequential dates and I have tried dragging down from the corner on a series of manually entered dates, but this does not work, presumable because there is a 3-day gap, then a two-day gap. The column looks like this (European date format):

Monday, 2 10 2023

Thursday, 5 10 2023

Monday, 9 10 2023

Thursday, 12 10 2023

... etc.

Answer 1

To get Mondays and Thursdays in the next 4 weeks starting on 2023-10-02, use this:

=let( 
  dates, sequence(4 * 7, 1, "2023-10-02"), 
  filter( 
    to_date(dates), 
    match(weekday(dates, 2), vstack(1, 4), 0) 
  ) 
)

This uses a convention where Monday is weekday 1, Thursday is 4 and Sunday is 7.

See let(), sequence(), filter(), vstack() and match().