Automated Counting of Towers (\`A La Bordelaise) [Or: Footnote to p. 81   of the Flajolet-Sedgewick Chef-d'{\oe}vre]
  The brilliant idea of Jean Betrema and Jean-Guy Penaud that proved the celebrated "three to the power n" theorem of Dominique Gouyou-Beauchamps and Xavier Viennot, counting towers of domino pieces is extended and used to enumerate much more general towers, where the pieces can be many i-mers. 
Shalosh B. Ekhad and Doron Zeilberger
math.CO