A226917 Number of non-sphere-homeomorphic crossing optimal 2-page book drawings of complete graph K_{2n+1}.

1, 4, 9, 25, 58, 142, 324, 748, 1672, 3736, 8208, 17968, 38944, 84064, 180288, 385216, 819328

Offset

2,2

Links

Table of n, a(n) for n=2..18.

Bernardo M. Ábrego, Oswin Aichholzer, Silvia Fernández-Merchant, Pedro Ramos, Gelasio Salazar, The 2-Page Crossing Number of K_n, arXiv:1206.5669 [math.CO], 2012.

Bernardo M. Ábrego, Oswin Aichholzer, Silvia Fernández-Merchant, Pedro Ramos, Gelasio Salazar, The 2-Page Crossing Number of K_n, Discrete Comput. Geom. 49 (2013), no. 4, 747--777. MR3068573

Formula

Conjecture: a(n) = 4*a(n-1) - 2*a(n-2) - 8*a(n-3) + 8*a(n-4); g.f.: -x^2*(5*x^3-5*x^2+1) / ((2*x-1)^2*(2*x^2-1)). - Colin Barker, May 08 2014

Crossrefs

Cf. A000241.

Sequence in context: A068373 A030481 A160190 * A032127 A181357 A244558

Adjacent sequences: A226914 A226915 A226916 * A226918 A226919 A226920

Keyword

nonn,more

Author

N. J. A. Sloane, Jul 01 2013

Status

approved