f ( row + 1 ) = { "" ( row < 0 ) f ( row / 26 ) & Chr ( Asc ( "A" ) + row mod 26 ) ( row ≥ 0 ) f(row+1)=left lbrace {matrix { {"\"\"" }#{(row<0)}## {f(left lfloor row / 26 right rfloor)"&"{Chr(Asc("\"A\"")+row mod{26})}}#{(row>=0)} } } right none