This is a possible solution to Challenge 1 – Single Formula for Fibonacci Numbers
There can be many solutions to a given problem in Excel. Below are solutions proposed by me –
A1 and drag down –
=IF(ROW()<3,ROW()-1,SUM(OFFSET($A$1,ROW()-3,0,2)))
=IF(ROW()<3,ROW()-1,SUM(INDIRECT("A"&ROW()-2&":A"&ROW()-1)))
If you belong to that class where you worry about volatality of OFFSET and INDIRECT, use below which uses INDEX and INDEX is a non-volatile function –
=IF(ROW()<3,ROW()-1,SUM(INDEX(A:A,ROW()-2):INDEX(A:A,ROW()-1)))