1,2

Alexander Stoimenow, On the number of chord diagrams, Discr. Math. 218 (2000), 209-233.

Formula due to V. A. Liskovets (liskov(AT)math.tu-dresden.de).

a(n) = A047974(n-1)+(n-1)*A047974(n-2). Essentially the same as A081126. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 06 2006

Sequence in context: A148397 A148398 A100442 this_sequence A081126 A006191 A149959

Adjacent sequences: A018188 A018189 A018190 this_sequence A018192 A018193 A018194

nonn

Alexander Stoimenow (stoimeno(AT)math.toronto.edu)