A269031 Number of n X 4 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once.

36, 216, 2166, 18384, 146064, 1114848, 8277072, 60218112, 431354928, 3052215072, 21383561232, 148585984320, 1025363155440, 7034327057760, 48013557090768, 326276117933952, 2208609401649072, 14899002865010592, 100198549907000208

Offset

1,1

Links

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

Formula

Empirical: a(n) = 14*a(n-1) - 57*a(n-2) + 56*a(n-3) - 16*a(n-4) for n>5.

Empirical g.f.: 6*x*(6 - 48*x + 199*x^2 - 274*x^3 + 105*x^4) / (1 - 7*x + 4*x^2)^2. - Colin Barker, Jan 18 2019

Example

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

Crossrefs

Column 4 of A269035.

Sequence in context: A230470 A066610 A176696 * A113164 A237252 A017234

Adjacent sequences: A269028 A269029 A269030 * A269032 A269033 A269034

Keyword

nonn

Author

R. H. Hardin, Feb 18 2016

Status

approved