Returns or sets the array formula of a range. Returns (or can be set to) a single formula or a Visual Basic array. If the specified range doesn't contain an array formula, this property returns Null. Read/write Variant.
Remarks
If you use this property to enter an array formula, the formula must use the R1C1 reference style, not the A1 reference style (see the second example).
Example
This example enters the number 3 as an array constant in cells A1:C5 on Sheet1.
Worksheets("Sheet1").Range("A1:C5").FormulaArray = "=3"
This example enters the array formula =SUM(R1C1:R3C3) in cells E1:E3 on Sheet1.
Worksheets("Sheet1").Range("E1:E3").FormulaArray = _
"=Sum(R1C1:R3C3)"