A185405 1/7 the number of n X 2 0..6 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 13, 150, 1848, 22656, 278832, 3430776, 42221928, 519611520, 6394769688, 78699293256, 968538893952, 11919644165496, 146693048343528, 1805326578739200, 22217849450044248, 273431322619829256

Offset

1,2

Comments

Column 2 of A185409.

Links

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

Formula

Empirical: a(n) = 11*a(n-1) + 23*a(n-2) - 72*a(n-3) - 144*a(n-4) - 216*a(n-5).

Empirical g.f.: x*(1 + 2*x - 16*x^2 - 29*x^3 - 42*x^4) / (1 - 11*x - 23*x^2 + 72*x^3 + 144*x^4 + 216*x^5). - Colin Barker, Apr 15 2018

Example

Some solutions for 3 X 2 with a(1,1)=0:
..0..0....0..0....0..0....0..0....0..0....0..2....0..3....0..0....0..0....0..0
..2..5....2..2....5..1....6..6....2..2....0..2....0..3....0..6....0..1....6..5
..2..5....5..5....5..1....5..5....4..4....3..3....3..3....6..6....0..1....6..5

Crossrefs

Cf. A185409.

Sequence in context: A163148 A355414 A345217 * A051475 A242576 A173448

Adjacent sequences: A185402 A185403 A185404 * A185406 A185407 A185408

Keyword

nonn

Author

R. H. Hardin, Jan 26 2011

Status

approved