A269272 Number of n X 4 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three exactly once.

108, 13896, 1104264, 74853576, 4684312584, 279339197256, 16128206816904, 909870855444936, 50443519266217224, 2758864964165996616, 149253876730080113544, 8002845140585293252296, 425920265748436386105864

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 20 2019: (Start)

G.f.: 36*x*(3 + 92*x + 49*x^2) / (1 - 49*x)^2.

a(n) = 72 * 49^(n-2) * (120*n-47) for n>1.

(End)

Example

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

Crossrefs

Column 4 of A269276.

Sequence in context: A269093 A113853 A209043 * A209015 A299951 A230273

Adjacent sequences: A269269 A269270 A269271 * A269273 A269274 A269275

Keyword

nonn

Author

R. H. Hardin, Feb 21 2016

Status

approved