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

It had to use a longer identifier for the key.

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9

The issue seems to be a duplicated key ID on the server. See the instructions from the CRAN and more background info on this post by Michael Rutter.