A067648 Number of knot diagrams of type 2PI with n crossings and two outgoing strings.

0, 2, 0, 2, 4, 12, 60, 226, 1076, 5156, 24984, 128548, 663040, 3514968, 18918792, 103123906, 569877652, 3180066004, 17921451960, 101842206548, 583109887600, 3361640932872, 19499226668816

Offset

0,2

Links

Table of n, a(n) for n=0..22.

J. L. Jacobsen and P. Zinn-Justin, A Transfer Matrix approach to the Enumeration of Knots

Crossrefs

Cf. A054993, A067647.

Sequence in context: A274414 A079550 A226430 * A279327 A052438 A324045

Adjacent sequences: A067645 A067646 A067647 * A067649 A067650 A067651

Keyword

nonn

Author

N. J. A. Sloane, Feb 05 2002

Extensions

Reference gives two further terms.

Status

approved