Installing R from CRAN Ubuntu repository: No Public Key Error

Question

I am on R version 2.13 and would like to update to a newer version in order to use some packages that depend on R>= 2.14.

I have the line to my sources.list file as

Answer 1

Thanks to Philipp Burckhardt, I got it fixed.

Try this:

gpg --keyserver pgpkeys.mit.edu --recv-key 51716619E084DAB9  
gpg -a --export 51716619E084DAB9 | sudo apt-key add -