Assuming that it's really a blank string, I think the following could work:
<colgroup><col style="width: 25pxpx"><col><col><col><col></colgroup><thead>
</thead><tbody>
[TD="align: center"]36[/TD]
[TD="align: right"]TRUE[/TD]
[TD="align: right"]38[/TD]
[TD="align: center"]37[/TD]
[TD="align: right"]FALSE[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: center"]38[/TD]
[TD="align: right"]FALSE[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: center"]39[/TD]
[TD="align: right"]TRUE[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: center"]40[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: center"]41[/TD]
[TD="align: right"]TRUE[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
</tbody>
Summary
[TABLE="width: 85%"]
<tbody>[TR]
[TD]
Worksheet Formulas[TABLE="width: 100%"]
<thead>[TR="bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]
[TH="width: 10px"]Cell[/TH]
[TH="align: left"]Formula[/TH]
[/TR]
</thead><tbody>[TR]
[TH="width: 10px, bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]D36[/TH]
[TD="align: left"]=AGGREGATE(
15,6,ROW(A36:A41)/IF((((A36:A41=FALSE)+(ISBLANK(A36:A41)))*(ISBLANK(B36:B41)))>0,1,0),1)[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
</tbody>[/TABLE]
In the formula:
Boolean logic (plus and multiply) is used to determine the rows that meet the criteria
The rest are errors due to divide by zero
The AGGREGATE function is used to pick the SMALLest number that is not an error