Put next number in sequence if cell not blank

[iddon17]

So A2 contains ID number 140686001

I want the next number in the sequence 140686002 to be generated in A3 only if B3 contains text

How do I do this?

 

[VBA Geek]

<b>Worksheet Formulas</b><table cellpadding="2.5px" width="100%" rules="all" style="border: 1px solid;text-align:center;background-color: rgb(255,255,255);border-collapse: collapse; border-color: rgb(187,187,187)"><thead><tr style=" background-color: rgb(218,231,245);color: rgb(22,17,32)"><th width="10px">Cell</th><th style="text-align:left;padding-left:5px;">Formula</th></tr></thead><tbody><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">A3</th><td style="text-align:left">=IF(<font color="Blue">B3<>"",MAX(<font color="Red">A$2:A2</font>)+1,""</font>)</td></tr></tbody></table></td></tr></table><br />

Excel 2010
	A	B
2	140686001
3	140686002	aaa
4
5	140686003	aa
6
7
8	140686004	aa
9	140686005	cc
10	140686006	aa
Sheet8