A216798 Number of permutations of an nX6 array with each element moving exactly one horizontally or vertically and without 2-loops.

0, 22, 32, 1774, 10140, 207408, 1879040, 27918806, 302667484, 3991662992, 46492284664, 585384941184, 7016484369112, 86745644666352, 1051690689056356, 12908451995027824, 157213197102215752, 1924102649175445120

Offset: 1

Author

R. H. Hardin Sep 17 2012

Keywords

• nonn

Comments

Column 6 of A216800

Examples

			Some solutions for n=4
..6..0..3..9..5.11....1..7..3..4..5.11....6..0..1..9..3..4....6..0..1..2..3..4
.12..1..2..8..4.10....0..6..2..8..9.10....7..8..2.10.16..5...12.13..7.10.16..5
.18..7.13.14.15.16...13.19.15.21.22.16...18.12.20.14.22.11...18.14..8..9.15.11
.19.20.21.22.23.17...12.18.14.20.23.17...19.13.21.15.23.17...19.20.21.22.23.17
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 9*a(n-1) +126*a(n-2) -895*a(n-3) -4784*a(n-4) +31216*a(n-5) +75941*a(n-6) -508196*a(n-7) -548324*a(n-8) +4278056*a(n-9) +1798234*a(n-10) -19820128*a(n-11) -2095562*a(n-12) [phone]*a(n-13) -985124*a(n-14) -76511412*a(n-15) +2082320*a(n-16) [phone]*a(n-17) +1713536*a(n-18) -20262336*a(n-19) -1935616*a(n-20) +1498112*a(n-21) +94208*a(n-22) -32768*a(n-23)