Number of Possible Usernames?

Assuming the max number of characters allowed in a username is 16, then the number would be 94^16, or 4.01907e26.

The more characters allowed in the username, the more possibilities. So, possible usernames=k^n, where k is the number of different characters one can incorporate into the username, and n is the number of characters in the username. 

Please comment if I missed any other variables.

Why do I write this? No reason. 

Sorry, miscalculation.

It should be 3.71574e31.

There are less when you consider the outlawed obscene possibilities.

Care to subtract for me?

Outlawed obscene possibilities?  I've seen "neighbourscumlover" on here before!

What is the longest username you have seen?

"neibourscumlover"  To be fair, I have a lot of negative things I could say about this person, so I easily remembered it.  There could have been longer names that I don't remember.