A Remark on Continued Fractions for Permutations and D-Permutations with a Weight -1 per Cycle

  • Bishal Deb
  • Alan D. Sokal


We show that very simple continued fractions can be obtained for the ordinary generating functions enumerating permutations or D-permutations with a large number of independent statistics, when each cycle is given a weight $-1$. The proof is based on a simple lemma relating the number of cycles modulo 2 to the numbers of fixed points, cycle peaks (or cycle valleys), and crossings.

Article Number