login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A226917 Number of non-sphere-homeomorphic crossing optimal 2-page book drawings of complete graph K_{2n+1}. 0
1, 4, 9, 25, 58, 142, 324, 748, 1672, 3736, 8208, 17968, 38944, 84064, 180288, 385216, 819328 (list; graph; refs; listen; history; text; internal format)
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: A068888 A030481 A160190 * A032127 A181357 A244558

Adjacent sequences:  A226914 A226915 A226916 * A226918 A226919 A226920

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 01 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 21 01:15 EST 2019. Contains 320364 sequences. (Running on oeis4.)