A183713 - OEIS

%I #11 Apr 04 2018 10:48:04

%S 12,54,224,950,4012,16964,71712,303170,1281664,5418314,22906232,

%T 96837444,409385940,1730703022,7316648160,30931557950,130764969444,

%U 552816553732,2337064300200,9880075964922,41768598769664,176579193270290

%N 1/20 of the number of (n+1) X 4 0..4 arrays with every 2 X 2 subblock strictly increasing clockwise or counterclockwise with one decrease.

%C Column 3 of A183719.

%H R. H. Hardin, <a href="/A183713/b183713.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 2*a(n-1) + 10*a(n-2) - 10*a(n-4) - 2*a(n-5) + a(n-6).

%F Empirical g.f.: 2*x*(6 + 15*x - 2*x^2 - 19*x^3 - 4*x^4 + 2*x^5) / ((1 - x)*(1 + x)*(1 - 2*x - 9*x^2 - 2*x^3 + x^4)). - _Colin Barker_, Apr 04 2018

%e Some solutions for 3 X 4:

%e ..0..4..1..4....0..4..0..4....4..0..4..0....3..0..3..4....3..2..3..2

%e ..2..3..2..3....1..2..1..3....3..2..3..2....2..1..2..0....0..1..0..1

%e ..0..4..1..0....0..3..0..4....0..1..4..0....3..4..3..4....3..2..4..2

%e ...

%e ...L..R..L.......L..R..L.......R..L..R.......R..L..R.......L..R..L...

%e ...R..L..R.......R..L..R.......L..R..L.......L..R..L.......R..L..R...

%Y Cf. A183719.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 06 2011