1,2

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,

Index entries for sequences related to shoe lacings

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.

Cf. A078698, A078700, A078675.

a(n) = ( A078698(n) + A078700(n) ) / 2

Sequence in context: A003085 A053598 A102585 this_sequence A069569 A015196 A113098

Adjacent sequences: A078699 A078700 A078701 this_sequence A078703 A078704 A078705

nonn

Hugo Pfoertner (hugo(AT)pfoertner.org), Dec 18 2002