Submitting a Paper

We have been drowning in comment spam from clueless spambots that do not understand that we are something other than a blog. So we have to ask you a simple question to make sure you are human. Here we go:

What is the coefficient of x in the expansion of the twenty-first power of (2x+1)? Write the answer, using only digits, in the box below.

We regret the inconvenience.