A233157 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A233157

Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally or antidiagonally.

81, 384, 2592, 17496, 121176, 842616, 5871528, 40931568, 285366888, 1989557640, 13871104848, 96708780360, 674249796360, 4700843090928, 32774093555112, 228499694410248, 1593090904911120, 11106967289377032, 77437340197187976

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) - 15*a(n-2) + 6*a(n-3) for n>7.

Empirical g.f.: 3*x*(27 - 115*x + 117*x^2 - 186*x^3 + 96*x^4 - 360*x^5 + 216*x^6) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Oct 09 2018

EXAMPLE

Some solutions for n=5:

..0..1..0..0..0....1..2..2..1..2....0..0..1..2..1....2..1..0..0..1

..0..0..0..0..0....2..1..2..2..2....1..2..1..0..1....0..0..1..2..1

..1..0..0..0..0....2..2..2..2..1....1..0..1..2..2....0..0..1..2..1

..0..1..0..0..1....2..1..2..2..2....1..2..1..2..2....1..0..1..0..1

CROSSREFS

Row 4 of A233155.

Sequence in context: A205737 A236035 A236028 * A237108 A237101 A236618

Adjacent sequences: A233154 A233155 A233156 * A233158 A233159 A233160

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 05 2013

STATUS

approved