A278095 Number of n X 2 0..3 arrays with every element plus 1 mod 4 equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.

0, 2, 10, 58, 334, 1910, 10910, 62314, 355898, 2032630, 11608866, 66301138, 378662314, 2162634690, 12351344662, 70541601526, 402880631914, 2300951495750, 13141306298158, 75053268849534, 428647886076278, 2448114693124250

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) - a(n-2) - 3*a(n-3) - 3*a(n-4) - 6*a(n-5) + 2*a(n-7).

Empirical g.f.: 2*x^2*(1 - x + x^3) / (1 - 6*x + x^2 + 3*x^3 + 3*x^4 + 6*x^5 - 2*x^7). - Colin Barker, Feb 07 2019

Example

Some solutions for n=4:
..0..3. .0..3. .0..1. .0..1. .0..3. .0..1. .0..3. .0..1. .0..3. .0..3
..1..2. .1..2. .3..2. .3..2. .1..2. .1..2. .1..0. .3..2. .1..2. .1..0
..1..1. .2..1. .3..0. .2..3. .0..1. .0..3. .2..3. .0..3. .0..3. .2..3
..0..0. .3..0. .2..1. .1..0. .0..0. .3..2. .1..2. .1..2. .2..1. .2..1

Crossrefs

Column 2 of A278099.

Sequence in context: A371770 A369487 A248403 * A075870 A074608 A086871

Adjacent sequences: A278092 A278093 A278094 * A278096 A278097 A278098

Keyword

nonn

Author

R. H. Hardin, Nov 12 2016

Status

approved