

A234259


Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 2 (constant stress 1 X 1 tilings).


1



20, 46, 104, 244, 560, 1336, 3104, 7504, 17600, 42976, 101504, 249664, 592640, 1465216, 3490304, 8660224, 20679680, 51437056, 123029504, 306525184, 733982720, 1830762496, 4387119104, 10951020544, 26255605760, 65571905536, 157265199104
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OFFSET

1,1


LINKS

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


FORMULA

Empirical: a(n) = 2*a(n1) + 6*a(n2)  12*a(n3).
Conjectures from Colin Barker, Oct 14 2018: (Start)
G.f.: 2*x*(10 + 3*x  54*x^2) / ((1  2*x)*(1  6*x^2)).
a(n) = 2^(2+n) + 2^((3+n)/2)*3^((1+n)/2)*(1212*(1)^n+5*sqrt(6)+5*(1)^n*sqrt(6)).
(End)


EXAMPLE

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


CROSSREFS

Column 1 of A234266.
Sequence in context: A236474 A145220 A234266 * A135286 A338235 A177725
Adjacent sequences: A234256 A234257 A234258 * A234260 A234261 A234262


KEYWORD

nonn


AUTHOR

R. H. Hardin, Dec 22 2013


STATUS

approved



