Excel - 수식으로 고유값 추출

=IFERROR(INDEX(A$2:A$21, MATCH(0, COUNTIF($A1:A1, $A$2:A$21), 0)), "")

1.countif

https://xlworks.net/excel-function-countif/

2.match 함수

https://www.oppadu.com/%EC%97%91%EC%85%80-match-%ED%95%A8%EC%88%98/

3.index 함수

https://www.oppadu.com/%EC%97%91%EC%85%80-index-%ED%95%A8%EC%88%98/