A220783 Agreement numbers: number of n X 2 arrays of the count of horizontal and vertical neighbors equal to the corresponding element in a random 0..3 n X 2 array.

2, 11, 66, 388, 2292, 13524, 79820, 471076, 2780204, 16408196, 96837900, 571517860, 3372983916, 19906675140, 117485207756, 693374153956, 4092155315756, 24151080671492, 142534838636172, 841212055946788, 4964664988865004

Offset

1,1

Comments

Column 2 of A220786.

Links

R. H. Hardin, Table of n, a(n) for n = 1..179

Formula

Empirical: a(n) = 5*a(n-1) + 6*a(n-2) - 4*a(n-3).

Empirical g.f.: x*(2 - x)*(1 + x) / (1 - 5*x - 6*x^2 + 4*x^3). - Colin Barker, Mar 13 2018

Example

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

Crossrefs

Cf. A220786.

Sequence in context: A247109 A039632 A143816 * A160852 A185627 A216585

Adjacent sequences: A220780 A220781 A220782 * A220784 A220785 A220786

Keyword

nonn

Author

R. H. Hardin, Dec 20 2012

Status

approved