To avoid all problems with the reliable range of VBScript's Double/Currency numbers, split your start number (string) into a stable/never changing prefix and a Long number tail that gets incremented:
Option Explicit
Dim sStart : sStart = "12345678901234567"
Dim nCount : nCount = 20
Dim sPfx : sPfx = Left(sStart, 10)
Dim nStart : nStart = CLng(Mid(sStart, 11))
Dim n
For n = 1 To nCount
WScript.Echo sPfx, nStart, sPfx & nStart
nStart = nStart + 1
Next
output:
1234567890 1234567 12345678901234567
1234567890 1234568 12345678901234568
1234567890 1234569 12345678901234569
1234567890 1234570 12345678901234570
1234567890 1234571 12345678901234571
1234567890 1234572 12345678901234572
1234567890 1234573 12345678901234573
1234567890 1234574 12345678901234574
1234567890 1234575 12345678901234575
1234567890 1234576 12345678901234576
1234567890 1234577 12345678901234577
1234567890 1234578 12345678901234578
1234567890 1234579 12345678901234579
1234567890 1234580 12345678901234580
1234567890 1234581 12345678901234581
1234567890 1234582 12345678901234582
1234567890 1234583 12345678901234583
1234567890 1234584 12345678901234584
1234567890 1234585 12345678901234585
1234567890 1234586 12345678901234586