<IfModule mod_rewrite.c>

RewriteEngine on
RewriteBase /~se414017/
RewriteRule !^public/ public%{REQUEST_URI} [L]

RewriteCond %{THE_REQUEST} ^GET /public/
RewriteRule ^public/(.*) /$1 [L,R=301]

</IfModule>

Not Found

The requested URL /~username/public/~username/ was not found on this server.