A221900 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, without move-in move-out straight through or left turns.

6, 266, 7667, 236532, 7235107, 221465158, 6778558415, 207481075456, 6350624324828, 194381582401875, 5949680932424079, 182109354161412326, 5574049625663873593, 170611934699230942606, 5222133675326885401935

Offset: 1

Author

R. H. Hardin Jan 30 2013

Keywords

• nonn

Comments

Row 3 of A221898

Examples

			Some solutions for n=3
..2..1..0....1..0..1....0..2..0....1..3..2....0..0..1....1..2..2....0..0..4
..0..1..1....0..1..0....0..3..0....1..0..0....3..0..2....1..0..0....3..0..0
..1..2..1....3..1..2....2..1..1....0..0..2....0..2..1....1..0..2....0..2..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..129

Formula

Empirical: a(n) = 14*a(n-1) +401*a(n-2) +3090*a(n-3) +7741*a(n-4) -40484*a(n-5) -361940*a(n-6) -1090743*a(n-7) -1171988*a(n-8) +2002414*a(n-9) +720120*a(n-10) -7394610*a(n-11) [phone]*a(n-12) -2069693*a(n-13) -44623518*a(n-14) [phone]*a(n-15) -104778098*a(n-16) [phone]*a(n-17) [phone]*a(n-18) -174397406*a(n-19) [phone]*a(n-20) [phone]*a(n-21) -214551956*a(n-22) [phone]*a(n-23) [phone]*a(n-24) -10733620*a(n-25) +1466700*a(n-26) -21780*a(n-27) -2160*a(n-28)