A231134 Number of (n+1) X (2+1) black-square subarrays of 0..2 arrays with no element equal to a strict majority of its diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.

2, 9, 40, 182, 808, 3688, 16368, 74728, 331648, 1514160, 6719936, 30680320, 136161152, 621652928, 2758934016, 12596099456, 55902265856, 255225567744, 1132706802688, 5171449356800, 22951211032576, 104785303002112

Offset: 1

Author

R. H. Hardin, Nov 04 2013

Keywords

• nonn

Examples

			Some solutions for n=5:
..x..0..x....x..0..x....x..0..x....x..0..x....x..0..x....x..0..x....x..0..x
..1..x..2....1..x..0....1..x..2....1..x..1....0..x..1....0..x..1....1..x..2
..x..1..x....x..2..x....x..1..x....x..2..x....x..1..x....x..2..x....x..0..x
..0..x..0....0..x..0....0..x..1....1..x..1....2..x..0....2..x..0....1..x..2
..x..1..x....x..2..x....x..0..x....x..2..x....x..2..x....x..1..x....x..0..x
..2..x..0....1..x..0....2..x..2....0..x..0....0..x..0....2..x..0....2..x..2
		

Links

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

Crossrefs

Column 2 of A231137.

Formula

Empirical: a(n) = 22*a(n-2) - 36*a(n-4) + 16*a(n-6).

Empirical g.f.: x*(2 + 9*x - 4*x^2 - 16*x^3 + 8*x^5) / (1 - 22*x^2 + 36*x^4 - 16*x^6). - Colin Barker, Sep 26 2018