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A266007 Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors equal to itself. 1
2, 2, 6, 14, 22, 46, 102, 190, 374, 782, 1542, 3038, 6166, 12334, 24486, 49150, 98486, 196430, 393030, 786974, 1572694, 3144814, 6292710, 12583486, 25162742, 50333582, 100667526, 201318494, 402652822, 805322926, 1610596902, 3221208190 (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) = a(n-1) + 4*a(n-3).

Empirical g.f.: 2*x*(1 + 2*x^2) / ((1 - 2*x)*(1 + x + 2*x^2)). - Colin Barker, Jan 09 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A266012.

Sequence in context: A233230 A320070 A319866 * A051890 A071109 A005310

Adjacent sequences:  A266004 A266005 A266006 * A266008 A266009 A266010

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 20 2015

STATUS

approved

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Last modified September 28 19:54 EDT 2021. Contains 347717 sequences. (Running on oeis4.)