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A234731 Number of (n+1) X (1+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 8 (constant stress 1 X 1 tilings). 1
168, 672, 2184, 8736, 29976, 119904, 426120, 1704480, 6197208, 24788832, 91531464, 366125856, 1366929816, 5467719264, 20584483080, 82337932320, 312012926808, 1248051707232, 4754424175944, 19017696703776, 72763338316056 (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) = 4*a(n-1) + 34*a(n-2) - 136*a(n-3) - 369*a(n-4) + 1476*a(n-5) + 1260*a(n-6) - 5040*a(n-7).

Empirical g.f.: 24*x*(7 - 259*x^2 + 3090*x^4 - 11760*x^6) / ((1 - 4*x)*(1 - 7*x^2)*(1 - 12*x^2)*(1 - 15*x^2)). - Colin Barker, Oct 16 2018

EXAMPLE

Some solutions for n=5:

..1..7....7..2....1..5....2..6....7..2....0..4....3..6....1..5....7..3....5..0

..4..2....2..5....5..1....5..1....4..7....4..0....7..2....4..0....0..4....0..3

..0..6....5..0....3..7....2..6....6..1....2..6....2..5....3..7....4..0....6..1

..3..1....1..4....7..3....5..1....3..6....4..0....6..1....4..0....0..4....2..5

..1..7....7..2....0..4....1..5....5..0....0..4....3..6....2..6....4..0....7..2

..5..3....1..4....7..3....7..3....0..3....4..0....5..0....5..1....2..6....0..3

CROSSREFS

Column 1 of A234738.

Sequence in context: A137863 A266808 A234738 * A157998 A234823 A234816

Adjacent sequences:  A234728 A234729 A234730 * A234732 A234733 A234734

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2013

STATUS

approved

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Last modified July 28 17:14 EDT 2021. Contains 346335 sequences. (Running on oeis4.)