A078702 - OEIS

This site is supported by donations to The OEIS Foundation.

A078702

Number of ways to lace a shoe that has n pairs of eyelets such that each eyelet has at least one direct connection to the opposite side.

1, 2, 13, 213, 7584, 454380, 39665160, 4775586480 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`The lace is "undirected": reversing the order of eyelets along the path does not count as a different solution. It must begin and end at the extreme pair of eyelets,`
	LINKS	`Index entries for sequences related to shoe lacings`
	EXAMPLE	`a(3) = 13: label the eyelets 1,2,3 from front to back on the left side then 4,5,6 from back to front on the right side. The lacings are: 124356 154326 153426 142536 145236 135246 125346 124536 125436 152346 153246 152436 154236.`
	CROSSREFS	`Cf. A078698, A078700, A078675.` `a(n) = ( A078698(n) + A078700(n) ) / 2` `Sequence in context: A053598 A193550 A102585 * A069569 A015196 A187648` `Adjacent sequences: A078699 A078700 A078701 * A078703 A078704 A078705`
	KEYWORD	`nonn`
	AUTHOR	`Hugo Pfoertner (hugo(AT)pfoertner.org), Dec 18 2002`

Content is available under The OEIS End-User License Agreement .

Last modified February 15 17:13 EST 2012. Contains 205828 sequences.