A185561 - OEIS

A185561

1/4 the number of n X 3 0..3 arrays with no element equal both to the element above and to the element to its left.

16, 900, 50580, 2842560, 159749820, 8977824540, 504547256880, 28355191537860, 1593541291098420, 89555869973406240, 5032975230384726780, 282849573983126145660, 15895941831670877597520, 893340453575999346503940

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

OFFSET

1,1

COMMENTS

Column 3 of A185567.

LINKS

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

FORMULA

Empirical: a(n) = 57*a(n-1) - 45*a(n-2).

Empirical g.f.: 4*x*(4 - 3*x) / (1 - 57*x + 45*x^2). - Colin Barker, Apr 16 2018

EXAMPLE

Some solutions for 5 X 3 with a(1,1)=0:

..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0

..0..2..2....0..2..0....0..2..0....0..2..2....0..2..0....0..2..0....0..2..0

..2..0..1....0..1..3....0..2..1....0..3..2....0..1..0....0..3..2....0..2..3

..0..1..3....2..2..2....1..2..2....3..0..3....3..2..3....0..3..3....0..2..3

..3..3..0....1..2..0....3..3..3....0..3..1....0..1..0....3..1..0....1..1..3

CROSSREFS

Cf. A185567.

Sequence in context: A272468 A214386 A367089 * A369583 A283946 A289707

Adjacent sequences: A185558 A185559 A185560 * A185562 A185563 A185564

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 31 2011

STATUS

approved