Involutions and their progenies
  Any permutation has a disjoint cycle decomposition and concept generates an equivalence class on the symmetry group called the cycle-type. The main focus of this work is on permutations of restricted cycle-types, with particular emphasis on the special class of involutions and their partial sums. The paper provides generating functions, determinantal expressions, asymptotic estimates as well as arithmetic and combinatorial properties. 
Tewodros Amdeberhan, Victor H. Moll
math.CO