A067647 Number of knot diagrams of type 1PI with n crossings and two outgoing strings.

0, 2, 4, 18, 108, 748, 5648, 45234, 378300, 3271204, 29049824, 263656356, 2436827328, 22871937208, 217536523260, 2092958991474, 20341256951692, 199471121367508, 1971730006936240, 19630246152650228

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: A370524 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