A183731 1/16 the number of (n+1) X 3 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.

21, 290, 13169, 550268, 19849923, 667017027, 21320890377, 659741463420, 19939380387212, 592112324464323, 17343862233069362, 502495529472928971, 14428841233622907321, 411240107421964502725, 11647315145815312830954

Offset: 1

Author

R. H. Hardin, Jan 06 2011

Keywords

• nonn

Comments

Column 2 of A183738.

Examples

			Some solutions with the first block increasing clockwise for 3 X 3:
..7..0..6....6..7..0....3..5..4....6..1..7....0..2..0....0..1..2....0..2..7
..4..1..4....4..2..1....2..7..3....5..2..5....7..3..7....6..4..3....7..3..6
..3..2..3....6..7..0....1..0..1....4..3..4....6..4..5....7..1..2....5..4..5
...
...R..L.......R..R.......R..L.......R..L.......R..L.......R..R.......R..L...
...R..L.......L..L.......R..L.......R..L.......R..L.......L..L.......R..L...
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=59*a(n-1)-983*a(n-2)+1517*a(n-3)+56964*a(n-4)-301681*a(n-5)-391561*a(n-6)+6287597*a(n-7)-12340851*a(n-8)-17981853*a(n-9)[phone]*a(n-10)-42259832*a(n-11)-195169753*a(n-12)[phone]*a(n-13)[phone]*a(n-14)-407605405*a(n-15)[phone]*a(n-16)[phone]*a(n-17)-122546216*a(n-18)-125908592*a(n-19)[phone]*a(n-20)[phone]*a(n-21)-21987805*a(n-22)-3922294*a(n-23)+3666493*a(n-24)+284823*a(n-25)-339999*a(n-26)-7395*a(n-27)+16089*a(n-28)-300*a(n-29)-300*a(n-30)+16*a(n-31).