CUFP blazar I was thinking about <A HREF="http://www.google.com/search?q=conway+audioactive">Conway's audioactive sequence</A> and how easy it would be to write a perl program generating it. Well, here it is, as a oneliner: <CODE> perl -e '$_=1;print,s/((\d)\2*)/(length$1).$2/ge while~<>' </CODE> (this waits for user to press return before emitting the next term of the sequence.) <P>By comparison see e.g. this <A HREF="http://soy.dyndns.org/~peter/projects/math/audioactive/">link</A>. (Please note however that it's just a random hit from Google: don't consider it to have an absolute indicative power.)