Apparently the solution differs between Ubuntu versions. Following worked for me on Ubuntu 13.10:
sudo apt-get install nodejs-legacy
HTH
Edit: Rule of thumb:
If you have installed nodejs but are missing the /usr/bin/node binary, then also install nodejs-legacy. This just creates the missing softlink.
According to my tests, Ubuntu 17.10 and above already have the compatibility-softlink /usr/bin/node in place after nodejs is installed, so nodejs-legacy is missing from these releases as it is no more needed.
