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A067646 Number of prime alternating tangles (or knots) with two connected components. 2
1, 2, 4, 8, 24, 72, 264, 1074, 4490, 20296, 92768, 439148, 2118654, 10377708, 51740280, 260545092, 1328891356, 6836872181 (list; graph; refs; listen; history; text; internal format)
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 AntonioG. Astudillo (afg_astudillo(AT)lycos.com), Apr 21 2003

STATUS

approved

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Last modified May 26 19:44 EDT 2019. Contains 323597 sequences. (Running on oeis4.)