A185553 1/3 the number of nX3 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

1, 26, 224, 2530, 25496, 269496, 2792166, 29168100, 303674928, 3165976954, 32988466864, 343808442136, 3582861328974, 37338788146540, 389120024162368, 4055176375558754, 42260513291812936, 440413129026231448

Offset

1,2

Comments

Column 3 of A185559

Links

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

Formula

Empirical: a(n)=7*a(n-1)+41*a(n-2)-44*a(n-3)-111*a(n-4)-140*a(n-5)+291*a(n-6)-225*a(n-7)+511*a(n-8)+2150*a(n-9)-3007*a(n-10)-6248*a(n-11)-624*a(n-12)+19900*a(n-13)-14308*a(n-14)+15248*a(n-15)-13312*a(n-16)-1648*a(n-17)+21440*a(n-18)-5632*a(n-19)-3968*a(n-20)+5632*a(n-21)-14336*a(n-22)-8192*a(n-23)

Example

Some solutions for 4X3 with a(1,1)=0
..0..0..0....0..1..1....0..0..2....0..1..1....0..0..0....0..2..0....0..1..1
..1..1..1....0..0..1....2..2..2....0..1..1....1..2..2....0..2..0....0..0..1
..0..0..1....2..0..1....2..1..1....2..0..2....1..2..0....0..0..2....2..1..0
..0..1..1....2..2..1....0..0..1....2..0..2....2..2..0....2..2..2....2..1..0

Crossrefs

Sequence in context: A242262 A241938 A317865 * A269658 A220714 A159519

Adjacent sequences: A185550 A185551 A185552 * A185554 A185555 A185556

Keyword

nonn

Author

R. H. Hardin Jan 31 2011

Status

approved