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A230971 Number of (n+2) X (2+2) 0..3 arrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero. 1
16, 144, 1024, 9216, 85264, 767376, 6885376, 61968384, 557904400, 5021139600, 45188555776, 406697001984, 3660288323344, 32942594910096, 296483216441344, 2668348947972096, 24015141771494416, 216136275943449744 (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) = 9*a(n-1) - 8*a(n-2) + 72*a(n-3) + 9*a(n-4) - 81*a(n-5).

Empirical g.f.: 16*x*(1 - 3*x)*(1 + 3*x) / ((1 - x)*(1 + x)*(1 - 9*x)*(1 + 9*x^2)). - Colin Barker, Sep 25 2018

EXAMPLE

Some solutions for n=1:

..0..1..0..3....0..3..2..3....0..3..0..3....0..2..0..2....0..0..0..0

..2..1..0..3....2..1..0..3....2..1..0..3....1..1..3..3....3..1..1..3

..0..3..2..3....0..1..0..3....0..1..2..3....0..0..2..2....0..2..2..0

CROSSREFS

Column 2 of A230977.

Sequence in context: A000762 A217711 A086952 * A282524 A287168 A155663

Adjacent sequences:  A230968 A230969 A230970 * A230972 A230973 A230974

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 02 2013

STATUS

approved

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Last modified August 17 03:11 EDT 2022. Contains 356180 sequences. (Running on oeis4.)