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A237632 Number of (n+1) X (3+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
702, 1220, 1310, 1488, 2086, 2900, 4132, 5720, 8248, 11504, 16546, 22928, 33024, 46016, 66184, 91712, 132096, 184064, 264736, 366848, 528384, 736256, 1058944, 1467392, 2113536, 2945024, 4235776, 5869568, 8454144, 11780096, 16943104 (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-4) for n>13.

Empirical g.f.: 2*x*(351 + 610*x + 655*x^2 + 744*x^3 - 361*x^4 - 990*x^5 - 554*x^6 - 116*x^7 - 48*x^8 - 48*x^9 + 9*x^10 + 24*x^11 + 16*x^12) / ((1 - 2*x^2)*(1 + 2*x^2)). - Colin Barker, Oct 24 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Column 3 of A237637.

Sequence in context: A252575 A252566 A269542 * A304155 A305508 A305174

Adjacent sequences:  A237629 A237630 A237631 * A237633 A237634 A237635

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 10 2014

STATUS

approved

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Last modified January 25 14:14 EST 2022. Contains 350572 sequences. (Running on oeis4.)