It might help to explain the purpose.
I mean, Lightroom does not support remembered sequence number for exporting, but for most people, it's not a problem, because:
* they're either exporting a whole new set (and so continuing a sequence number is not desired), or
* they're using publishing services (and overwrite previous export with new copy, and so don't use sequence numbers at all).
A continued sequence number would be easy enough to implement via a plugin, but so far there hasn't been much demand (that I am aware of), and I dunno if you'd use a plugin for that anyway, or just do without..
Our workflow treats photos as items requiring serial numbers. We create about 30,000 images a year. But we create many hundreds or thousands of other items, too. Our digital asset management system (which handles and tracks all of our digital media, everything). Because there are so many photos, it's easier to use a sequential counter that creates a unique serial number than to rename everything. Aperture remembered the last number used. It was a great feature. That Lightroom cannot or will not do this is silly. At least it should be an option for those of us who need sequential numbering all the time. Apple assumed it was a good idea and allowed it to be done without thinking about it. About every third or fourth import I have to go back and rename a couple thousand images because Lightroom just reuses the same numbers unless you diligently keep track of where you left off last import. It's tedious and dumb. But there were lots of dumb things in Aperture and I'm glad it's dead.
I see - thanks.
Fingers crossed for persistent sequence number in Lr6..