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A235080 Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 4, with no adjacent elements equal (constant stress tilted 1 X 1 tilings). 1
38, 90, 202, 478, 1078, 2554, 5786, 13726, 31238, 74202, 169642, 403486, 926614, 2206714, 5090042, 12136798, 28113638, 67114074, 156091786, 373047646, 870937078, 2083671802, 4882030682, 11691483166, 27483747014, 65877727194 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - 10*a(n-3) - 5*a(n-4).

Empirical g.f.: 2*x*(19 + 7*x - 103*x^2 - 43*x^3) / ((1 - 2*x - x^2)*(1 - 5*x^2)). - Colin Barker, Oct 17 2018

EXAMPLE

Some solutions for n=5:

..2..0....2..3....2..3....1..4....4..2....3..2....4..2....1..4....2..1....3..2

..1..3....3..0....3..0....3..2....1..3....0..3....1..3....3..2....0..3....0..3

..3..1....1..2....1..2....0..3....3..1....2..1....4..2....0..3....3..2....3..2

..1..3....4..1....3..0....1..0....2..4....0..3....2..4....2..1....0..3....1..4

..2..0....1..2....2..3....0..3....4..2....1..0....4..2....0..3....2..1....3..2

..0..2....3..0....3..0....1..0....2..4....0..3....1..3....3..2....1..4....0..3

CROSSREFS

Column 1 of A235087.

Sequence in context: A014716 A137028 A235087 * A218331 A124141 A093649

Adjacent sequences:  A235077 A235078 A235079 * A235081 A235082 A235083

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 03 2014

STATUS

approved

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Last modified May 9 19:07 EDT 2021. Contains 343746 sequences. (Running on oeis4.)