A185535 1/6 the number of n X 2 0..5 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 11, 110, 1155, 12105, 127190, 1336205, 14039455, 147510990, 1549891055, 16284627805, 171101820790, 1797758782905, 18888967243155, 198465493076590, 2085267630701755, 21909809227375505, 230205338311698390

Offset

1,2

Comments

Column 2 of A185540.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) + 19*a(n-2) - 25*a(n-3) - 75*a(n-4) - 125*a(n-5).

Empirical g.f.: x*(1 + 2*x - 8*x^2 - 19*x^3 - 30*x^4) / (1 - 9*x - 19*x^2 + 25*x^3 + 75*x^4 + 125*x^5). - Colin Barker, Apr 16 2018

Example

Some solutions for 3 X 2 with a(1,1)=0:
..0..4....0..0....0..0....0..0....0..0....0..0....0..3....0..5....0..0....0..5
..0..4....5..1....0..5....1..1....1..3....0..2....0..3....0..5....2..0....0..5
..0..4....5..1....0..5....3..3....1..3....2..2....3..3....3..3....2..0....5..5

Crossrefs

Cf. A185540.

Sequence in context: A285561 A285541 A355407 * A281601 A266513 A356329

Adjacent sequences: A185532 A185533 A185534 * A185536 A185537 A185538

Keyword

nonn

Author

R. H. Hardin, Jan 30 2011

Status

approved