A067646 Number of prime alternating tangles (or knots) with two connected components.

1, 2, 4, 8, 24, 72, 264, 1074, 4490, 20296, 92768, 439148, 2118654, 10377708, 51740280, 260545092, 1328891356, 6836872181

Offset

0,2

Links

Table of n, a(n) for n=0..17.

S. R. Finch, Knots, links and tangles

S. R. Finch, Knots, links and tangles, Aug 08 2003. [Cached copy, with permission of the author]

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

Crossrefs

Equals A067644 + 2*A067645.

Sequence in context: A115115 A026097 A264557 * A152875 A179190 A291482

Adjacent sequences: A067643 A067644 A067645 * A067647 A067648 A067649

Keyword

nonn

Author

N. J. A. Sloane, Feb 05 2002

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 21 2003

Status

approved