A212715 Number of nonintersecting (or self-avoiding) knight paths joining opposite corners of an n X n grid.

1, 0, 2, 138, 88920, 752404294

Offset: 1

Author

Alex Ratushnyak, May 24 2012

Keywords

• nonn
• walk

Examples

			When n=3 this is the number of ways to move a knight from a1 to c3 without occupying any cell twice. Only two paths: a1-b3-c1-a2-c3 and a1-c2-a3-b1-c3.
When n=8 this is the number of ways to move a knight from a1 to h8 without occupying any cell twice.
		

Crossrefs

Cf. A007764 : rook paths (with moves of unit length).

Cf. A038496 : bishop paths (with moves of unit length).

Cf. A140518 : king paths.

Programs

C

#include 
int WIDTH, HEIGHT;
char grid[16][16];
int calc_ways(int x, int y) {
    if (!((unsigned)x