

A234927


Number of (n+2) X (1+2) 0..2 arrays with each 3 X 3 subblock having the sum of its 72 absolute element differences equal to 34 and no adjacent elements equal.


1



56, 88, 138, 176, 312, 432, 584, 960, 1408, 1872, 3168, 4544, 6080, 10176, 14720, 19648, 33024, 47616, 63616, 106752, 154112, 205824, 345600, 498688, 666112, 1118208, 1613824, 2155520, 3618816, 5222400, 6975488, 11710464, 16900096
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OFFSET

1,1


LINKS



FORMULA

Empirical: a(n) = 2*a(n3) + 4*a(n6) for n>9.
Empirical g.f.: 2*x*(28 + 44*x + 69*x^2 + 32*x^3 + 68*x^4 + 78*x^5 + 4*x^6  8*x^7  4*x^8) / (1  2*x^3  4*x^6).  Colin Barker, Oct 16 2018


EXAMPLE

Some solutions for n=5:
..0..2..1....0..1..2....1..2..0....0..1..2....1..2..0....0..2..1....2..0..2
..2..1..2....1..2..1....2..0..1....1..2..0....2..0..2....2..1..2....1..2..1
..1..2..0....2..0..2....0..1..0....2..1..2....1..2..1....1..2..0....2..0..2
..2..0..1....1..2..0....1..0..2....0..2..1....2..0..2....2..0..2....1..2..0
..0..1..0....2..1..2....0..2..1....1..0..2....1..2..0....1..2..1....2..1..2
..1..0..2....0..2..1....2..1..2....0..1..0....2..1..2....2..0..2....1..2..0
..0..2..0....1..0..2....0..2..1....1..0..2....0..2..1....1..2..0....0..1..2


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



