Below is a possible solution to the challenge - Challenge 60 - Generate a list of 2nd and 4th Saturdays for a Year

Drag the below formula down

=IF(ROWS($1:1)<25,FLOOR(DATE($A$1,ROUNDUP(ROWS($1:1)/2,0),
2*(MOD(ROWS($1:1)-1,2)+1)*7),7),"")