Automatically restart formula given that parameter is met?

[singhm]

Hi Experts,

I am in need of some assistance. I have a list of multiple id's in column A, column b contains data of the number of items linked to the ID. I want to generate a list of every page pertaining to each ID as follows, so i want in column C (for example) "a - Page 0001" all the way until "a - 1000" given that a had 1000 pages but then when it reaches 1000, i want it to restart from b as follows:

[TABLE="width: 481"]
<colgroup><col><col><col></colgroup><tbody>[TR]
[TD]a[/TD]
[TD]1000[/TD]
[TD]a - Page 0001[/TD]
[/TR]
[TR]
[TD]b[/TD]
[TD]2000[/TD]
[TD]a - Page 0002[/TD]
[/TR]
[TR]
[TD]c[/TD]
[TD]1500[/TD]
[TD]a - Page 0003[/TD]
[/TR]
[TR]
[TD]d[/TD]
[TD]1200[/TD]
[TD]a - Page 0004[/TD]
[/TR]
[TR]
[TD]e[/TD]
[TD]700[/TD]
[TD]…[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]a - Page 1000[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]b - Page 0001[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]b - Page 0002[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]b - Page 0003
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]b - Page 0004
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]…
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]b - Page 2000[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]c - Page 0001
[/TD]
[/TR]
</tbody>[/TABLE]

I have tried using the following formula:

=IF(ROW(C1)< B1+1,CONCATENATE($A$1," - Page ",TEXT(ROW(C1),"0000"),""))

The problem is that once it reaches 1000 i get errors (#VALUE!), firstly, I believe i have to $ the &A$1 otherwise when i drag the formula down it will just refer to the column to the left an i'll get a - Page 0001, b - page 0002, etc. Secondly, i am using the ROW function in order to generate the page numbers but i dont understand how i can force it to restart from 1 once it reaches the maximum (i.e 1000 for a).

I hope you can help.

Kind regards,
Manpaal Singh