Prohibited User Names regexp

Some update of the past year has rendered my regexp for prohibited user useless.
The correct, tested and working regexp is:
/^(?!((paula)|(admin)|:alpha:{1,2}\d))/
Some time over the past year or so my regexp was modified to:
/^(?!((paula)|(admin)|:alpha:{1, 2}\d))/
You will notice that there is a space added to the qualifier {1,2}
Regexp interpreters fail on the space in the qualifier.
I attempted to edit and save this regexp but when I go back and look the space has been added back in.
Basically, regexp with numerical from/to qualifier is broken.
Please help. This regexp on my site eliminates spam registrations that I have to service.
Thank you.

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