A185819 1/5 the number of nX3 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

1, 76, 1584, 49036, 1266624, 35446376, 956312244, 26231137608, 714107480512, 19507209473948, 532049001583280, 14521612514267224, 396222067735245796, 10812492512879834968, 295042237941175359056, 8051107927651445871340

Offset

1,2

Comments

Column 3 of A185825

Links

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

Formula

Empirical: a(n)=17*a(n-1)+327*a(n-2)-1020*a(n-3)-6773*a(n-4)+2794*a(n-5)+32525*a(n-6)+131655*a(n-7)-337771*a(n-8)+33788*a(n-9)+517885*a(n-10)-1145646*a(n-11)-5007180*a(n-12)+7715688*a(n-13)+39324336*a(n-14)-82942336*a(n-15)-35554304*a(n-16)+265939200*a(n-17)+170422272*a(n-18)-172261376*a(n-19)-774750208*a(n-20)-958660608*a(n-21)-1396703232*a(n-22)-1811939328*a(n-23)

Example

Some solutions for 4X3 with a(1,1)=0
..0..1..1....0..3..3....0..3..1....0..0..1....0..2..3....0..0..2....0..0..2
..0..1..0....0..4..3....0..3..1....0..1..1....0..2..3....0..2..2....4..4..2
..0..0..0....4..4..2....0..2..2....2..1..3....0..2..4....4..4..4....1..4..4
..1..1..1....4..2..2....1..1..2....2..1..3....0..2..4....1..1..1....1..1..1

Crossrefs

Sequence in context: A163710 A293310 A061618 * A270960 A060190 A156399

Adjacent sequences: A185816 A185817 A185818 * A185820 A185821 A185822

Keyword

nonn

Author

R. H. Hardin Feb 05 2011

Status

approved