%I #8 Oct 06 2015 22:06:56
%S 0,21,563,9403,135578,1814815,23204876,287769879,3491293862,
%T 41667398364,490998416023,5727556631915,66266101711488,
%U 761498455531330,8701271226331052,98948856313647335,1120614615517688964
%N 1/16 the number of (n+1) X 2 0..7 arrays with every 2 X 2 subblock strictly increasing clockwise or counterclockwise with one decrease, and at least two adjacent blocks having the same increasing direction.
%C Column 1 of A183738.
%H R. H. Hardin, <a href="/A183730/b183730.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n)=18*a(n-1)-46*a(n-2)-342*a(n-3)-33*a(n-4)+435*a(n-5)-157*a(n-6)-37*a(n-7)+21*a(n-8)-2*a(n-9).
%e Some solutions with the first block increasing clockwise for 3 X 2:
%e ..4..5....6..0....1..2....1..2....2..4....4..5....7..0....2..3....0..2....0..2
%e ..2..6....5..1....7..4....0..3....0..5....1..6....6..1....1..4....7..3....6..3
%e ..1..7....4..2....6..5....7..4....7..6....0..7....4..3....0..7....6..4....5..4
%e ...
%e ...R.......R.......R.......R.......R.......R.......R.......R.......R.......R...
%e ...R.......R.......R.......R.......R.......R.......R.......R.......R.......R...
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 06 2011