Combine multiple columns into one single column in Excel and Google Sheets

=OFFSET($A$2,CEILING(ROW(A2)/COLUMNS(A2:B5),1)-1,MOD(ROW(A2)-1+COLUMNS(A2:B5),2))

$A$2 = fixed cell; A2 = dynamic cell; A2:B5 = data range

Check below for a detailed explanation with pictures and how to use formulas in Excel and Google Sheets.