A018193 Number of chord diagrams of degree n with an isolated chord of length 1.

1, 1, 3, 11, 69, 602, 6531, 84737, 1271143, 21623667, 411133711, 8639077230, 198801435313, 4972210166209, 134299831740091, 3895950849227855, 120808412263797173, 3987662458459383826, 139598735205063044939

Offset

1,3

Links

Table of n, a(n) for n=1..19.

D. Bar-Natan, On the Vassiliev Knot Invariants, Topology 34 (1995) 423-472.

D. Bar-Natan, Bibliography of Vassiliev Invariants

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

Mathematica

Stoimenow states that a Mma package is available from his website. - N. J. A. Sloane, Jul 26 2018

Crossrefs

Sequence in context: A074504 A126115 A342057 * A121945 A009025 A009103

Adjacent sequences: A018190 A018191 A018192 * A018194 A018195 A018196

Keyword

nonn

Author

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

Extensions

More terms from Sean A. Irvine, Feb 04 2019

Status

approved