Dont trigger code if -1 column of target column has already value Worksheet change event

hi,
i am using this code to add some formulas when i input data in range f10:f1000
if cells(Target.Row, "E") has already formula or value then don't trigger this code

thank you

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Cells.Count > 1 Then Exit Sub
If Target = "" Then Exit Sub
If Not Intersect(Target, Range("F10:F1000")) Is Nothing Then
    Cells(Target.Row, "A") = "=IFERROR(INDEX(ENTRY_SSP,MATCH(RC[5],ENTRY_CODE,0)),"""")"
    Cells(Target.Row, "B") = IFERROR(IND"=EX(ENTRY_NAMES,MATCH(RC[4],ENTRY_CODE,0)),"""")"
    Cells(Target.Row, "C") = "=IFERROR(INDEX(ENTRY_MANID,MATCH(RC[3],ENTRY_CODE,0)),"""")"
    Cells(Target.Row, "D") = "=IFERROR(INDEX(ENTRY_NNN,MATCH(RC[2],ENTRY_CODE,0)),"""")"
    Cells(Target.Row, "E") = "=IF(ROW()=10,""1"",R[-1]C+1)"
End Sub

i mean trigger only one time when i put value in range f10:f1000

for example
i input some data in range f10
then this will add this formula to

a10= formula
b10= formula
c10= formula
d10= formula
e10= formula

and again i type some data in f10
now dont trigger the code because a10, b10, c10.....ae10 have already formulas

thank