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A067647 Number of knot diagrams of type 1PI with n crossings and two outgoing strings. 2
0, 2, 4, 18, 108, 748, 5648, 45234, 378300, 3271204, 29049824, 263656356, 2436827328, 22871937208, 217536523260, 2092958991474, 20341256951692, 199471121367508, 1971730006936240, 19630246152650228 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

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

CROSSREFS

Cf. A054993, A067648.

Sequence in context: A020101 A099938 A135069 * A208358 A213793 A287612

Adjacent sequences:  A067644 A067645 A067646 * A067648 A067649 A067650

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 05 2002

EXTENSIONS

Reference gives two further terms.

STATUS

approved

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Last modified June 26 04:11 EDT 2019. Contains 324369 sequences. (Running on oeis4.)