As I wrote there is a way to found them
Steemit redirects me to https://steemit.com/created
So I need to add /memechallenge in link bar to see them in order..
Please fix this bug
But #memechallenge tag is not now in "popular tags" so when I press New I cannot find anywhere #memechallenge
OK, right, it looks like a bug, posted on GitHub:
https://github.com/steemit/condenser/issues/1276
Thanks @gtg :)