I just joined, moving to LibreCalc after many years on Excel. I wrote a short and simple function to convert column numbers to letters. Maybe useful for someone? I also wrote one to convert column letters to numbers.
(They have no error corrections and accept column numbers >16,384!)
'Return column letters from number
Function aCol(i) as String
do while i > 0
aCol = Chr(i - 26*int((i-0.1)/26) + 64) & aCol: i = int((i-0.1)/26)
loop
End Function
'Return column number from letters
Function iCol(a) as Double
do while len(a) > 0
iCol = iCol*26 + asc(left(a,1))-64: a = right(a,len(a)-1)
loop
End Function