A181398 Summed lengths of nonintersecting rook paths on an n X n board.

0, 4, 64, 1912, 148432, 32871240, 20744801272, 37559607987584, 198461813970383240, 3100218604533034920976, 144170284249598867501946128, 20038589080922552365824887715432, 8349298401437323416105571304163524760, 10453318954664242363219930783045003561923656

Offset: 1

Author

David Scambler, Oct 17 2010

Keywords

• nonn

Comments

Paths are self-avoiding from one corner to the diagonally opposite corner.

Examples

			For 2 x 2: right+down (length 2), down+right (length 2), s(2) = 2+2 = 4
		

Crossrefs

Main diagonal of A181399.

Related sequences A181394, A181395, A181396, A181397.

Extensions

a(7)-a(14) from Andrew Howroyd, Jan 07 2020