A233838 Number of (n+2) X (1+2) 0..3 arrays with no increasing sequence of length 3 horizontally or antidiagonally downwards.

201664, 11305216, 633584640, 35508588544, 1990039158784, 111529525575680, 6250547858112512, 350304982786899968, 19632452026203373568, 1100278875554043658240, 61663902317168713269248

Offset

1,1

Links

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

Formula

Empirical: a(n) = 56*a(n-1) + 16*a(n-2) - 768*a(n-3) + 512*a(n-4).

Empirical g.f.: 64*x*(3151 + 188*x - 42720*x^2 + 28800*x^3) / ((1 + 4*x)*(1 - 60*x + 224*x^2 - 128*x^3)). - Colin Barker, Oct 11 2018

Example

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

Crossrefs

Column 1 of A233845.

Sequence in context: A241060 A233845 A233846 * A233837 A252498 A355332

Adjacent sequences: A233835 A233836 A233837 * A233839 A233840 A233841

Keyword

nonn

Author

R. H. Hardin, Dec 16 2013

Status

approved