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A237630 Number of (n+1) X (1+1) 0..2 arrays with the upper median of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one. 1
81, 260, 702, 1786, 4621, 11936, 30656, 77576, 200452, 515424, 1325424, 3365664, 8687760, 22278912, 57336960, 145904256, 376379712, 963592704, 2481143040, 6321940992, 16301843712, 41692741632, 107387375616, 273842325504 (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) = 36*a(n-4) + 48*a(n-6) for n>9.

Empirical g.f.: x*(81 + 260*x + 702*x^2 + 1786*x^3 + 1705*x^4 + 2576*x^5 + 1496*x^6 + 800*x^7 + 400*x^8) / (1 - 36*x^4 - 48*x^6). - Colin Barker, Oct 23 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Column 1 of A237637.

Sequence in context: A237060 A340697 A237637 * A236746 A236739 A237234

Adjacent sequences:  A237627 A237628 A237629 * A237631 A237632 A237633

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 10 2014

STATUS

approved

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Last modified January 19 06:18 EST 2022. Contains 350464 sequences. (Running on oeis4.)