Copy cell value to a range of cells - vba

Question

I'm new to VBA and I am trying to copy values from one cell to multiple cells when its value changes.
The value of A2 is constantly changing and when that happens I want that value to be copied to cells C2:C21 (and then eventually to cells D2:D21)
Here is an example of what I would like to achieve:
http://i.stack.imgur.com/xJZyZ.jpg
So far I wrote this code:
Sub Worksheet_Change(ByVal Target As Range)
For i = 0 To 19
If Not Intersect(Target, Range("AS2")) Is Nothing Then
Cells(Target.Row + i, 58).Value = Cells(Target.Row, 45).Value
End If
Next i
End Sub
but this only copies one single value of A2 to all the cells C2 to C22.
May anyone help me write this code properly?

Answer 1

Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("AS2")) Is Nothing Then
For CurCol = 3 to 4
For CurRow = 2 to 21
If Cells(CurRow, CurCol).Value = "" Then
Cells(CurRow, CurCol).Value = Target.Value
Exit Sub
EndIf
Next CurRow
Next CurCol
End If
End Sub

Answer 2

I guess this is what you're after:
Option Explicit
Sub Worksheet_Change(ByVal Target As Range)
Dim nVals As Long
If Not Intersect(Target, Range("A2")) Is Nothing Then
With Range("C2:D21")
nVals = WorksheetFunction.CountA(.Cells)
If nVals = .Count Then Exit Sub
Application.EnableEvents = False
On Error GoTo exitsub
.Cells(nVals Mod .Rows.Count + 1, IIf(nVals >= .Rows.Count, 2, 1)).Value = Target.Value
End With
End If
exitsub:
Application.EnableEvents = True
End Sub