A209539 - OEIS

%I #5 Mar 31 2012 12:37:29

%S 1,4,72,729,6480,63504,635040,6350400,63504000,635040000,6350400000,

%T 63504000000,635040000000,6350400000000,63504000000000,

%U 635040000000000,6350400000000000,63504000000000000,635040000000000000

%N Number of nX4 array permutations with every element making zero or one right-handed knight moves (out 2, right 1)

%C Column 4 of A209543

%H R. H. Hardin, <a href="/A209539/b209539.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 10*a(n-1) for n>6

%e Some solutions for n=4

%e ..6..7..9..3....0..8..2..3....6..7..2.10....0..7..9..3....6..1..2..3

%e .10..5..0..1...10.12.13.14....4.12..0..1....4..5..6..1....4.11..0.14

%e .14..2..4.11....1..9..4.11...14.15..3.11....8..2.10.11....8..9.10..5

%e .12.13..8.15....5..6..7.15....5.13..8..9...12.13.14.15...12.13..7.15

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 10 2012