Try this adaptation of a previous post by Glenn Schwandt in
..worksheet.functions (Mar 2001)
Put in any starting cell, say, B2:
=UPPER(IF(ROWS($A$1:A1)>18278,CHAR(96+INT(MOD(ROWS($A$1:A1)-18279,456976)/17
576)+1),"")&
IF(ROWS($A$1:A1)>702,CHAR(96+INT(MOD(ROWS($A$1:A1)-703,17576)/676)+1),"")&IF
(ROWS($A$1:A1)>26,
CHAR(96+INT(MOD(ROWS($A$1:A1)-27,676)/26)+1),"")&CHAR(97+MOD(ROWS($A$1:A1)-1
,26)))
Copy B2 down to B257 to fill: A, B, C ... IV
The formula can fill in the alpha series beyond IV to the extent of Excel's
65536 rows, viz. filling B2 to B65536 will return the alpha series: A, B, C
.... CRXO !
If filling across, just edit > replace :ROWS($A$1:A1)
with: COLUMNS($A$1:A1)
in the formula, viz. use in the starting cell:
=UPPER(IF(COLUMNS($A$1:A1)>18278,CHAR(96+INT(MOD(COLUMNS($A$1:A1)-18279,4569
76)/17576)+1),"")&
IF(COLUMNS($A$1:A1)>702,CHAR(96+INT(MOD(COLUMNS($A$1:A1)-703,17576)/676)+1),
"")&IF(COLUMNS($A$1:A1)>26,
CHAR(96+INT(MOD(COLUMNS($A$1:A1)-27,676)/26)+1),"")&CHAR(97+MOD(COLUMNS($A$1
:A1)-1,26)))