A221822 Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without consecutive moves in the same direction

6, 252, 6711, 190756, 5374720, 151592441, 4274867564, 120554575328, 3399703708400, 95873611077468, 2703690754567558, 76245627705373885, 2150170395738132532, 60636036995518426808, 1709970985328543058485

Offset

1,1

Comments

Column 3 of A221824

Links

R. H. Hardin, Table of n, a(n) for n = 1..180

Formula

Empirical: a(n) = 18*a(n-1) +312*a(n-2) -187*a(n-3) -13565*a(n-4) -20614*a(n-5) +158772*a(n-6) +381840*a(n-7) -1501245*a(n-8) -3110200*a(n-9) +13397334*a(n-10) -5218282*a(n-11) -30257641*a(n-12) +22527453*a(n-13) +59810156*a(n-14) -71002519*a(n-15) -62823023*a(n-16) +51211271*a(n-17) +211220974*a(n-18) -214821233*a(n-19) -158156578*a(n-20) +147778970*a(n-21) +223640148*a(n-22) -182698582*a(n-23) +171412*a(n-24) -59513311*a(n-25) +67158528*a(n-26) -136639431*a(n-27) +148395775*a(n-28) -84660389*a(n-29) +39605263*a(n-30) -6661260*a(n-31) +3867558*a(n-32) -132564*a(n-33) +150444*a(n-34) -5832*a(n-35)

Example

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

Crossrefs

Sequence in context: A281054 A056238 A335158 * A361186 A184424 A324478

Adjacent sequences: A221819 A221820 A221821 * A221823 A221824 A221825

Keyword

nonn

Author

R. H. Hardin Jan 26 2013

Status

approved