Random numbers but 3 numbers in sequence not allowed.

My worksheet has 20 columns and 500 rows. I wanted to populate my worksheet with random numbers: 6 numbers in every row. Problem is I do not want any row with 3 or more numbers in sequence eg 3-4-5 , 12-13-14, 15-16-17-18 etc. I try to modify some code I copy from somewhere to suit my need but the more I do, the more I get confused. Please help, somebody.

For J = 1 To 500
 
      For I = 1 To 20
            my(I) = I
      Next I
 
     For K = 1 To 6 'pick 6 number per row
     Randomize
     NewNumber:
     Number = Int(20 * Rnd) + 1
     If my(Number) = "" Then
         GoTo NewNumber
     Else
        Cells(j + 1, Number + 1) = my(Number)
         my(Number) = ""
    End If
    Next K
Next j