

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
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OFFSET

1,1


LINKS

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


FORMULA

Empirical: a(n) = 36*a(n4) + 48*a(n6) 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



