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

Author

R. H. Hardin, Feb 21 2016

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 4 of A269276.

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)