A269285 Number of n X 4 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once.

216, 19188, 1363572, 87559668, 5306911092, 309846524148, 17623065834612, 983118947312628, 54032675767734132, 2934733632740325108, 157871441490222209652, 8425105813832255961588, 446611038737537558861172

Offset

1,1

Links

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

Formula

Empirical: a(n) = 98*a(n-1) - 2401*a(n-2) for n>3.

Conjectures from Colin Barker, Jan 21 2019: (Start)

G.f.: 36*x*(1 - x)*(6 - 49*x) / (1 - 49*x)^2.

a(n) = 36 * (49^(n-2) * (240*n+53)) for n>1.

(End)

Example

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

Crossrefs

Column 4 of A269289.

Sequence in context: A223359 A046234 A229408 * A133052 A365629 A078204

Adjacent sequences: A269282 A269283 A269284 * A269286 A269287 A269288

Keyword

nonn

Author

R. H. Hardin, Feb 21 2016

Status

approved