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A196906 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,1,2,0,4 for x=0,1,2,3,4. 2
2, 6, 13, 34, 81, 199, 487, 1190, 2910, 7115, 17398, 42539, 104013, 254325, 621854, 1520506, 3717817, 9090502, 22227349, 54348491, 132888475, 324928002, 794487306, 1942615215, 4749923434, 11614123295, 28397901945, 69436221265, 169779754602 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Every 0 is next to 0 3's, every 1 is next to 1 1's, every 2 is next to 2 2's, every 3 is next to 3 0's, every 4 is next to 4 4's.

Column 2 of A196912.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = a(n-1) + 2*a(n-2) + 3*a(n-3) + 2*a(n-4) - a(n-6).

Empirical g.f.: x*(2 + 4*x + 3*x^2 + 3*x^3 - x^4 - x^5) / (1 - x - 2*x^2 - 3*x^3 - 2*x^4 + x^6). - Colin Barker, Mar 01 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A196912.

Sequence in context: A098407 A151390 A116426 * A162057 A026550 A319751

Adjacent sequences:  A196903 A196904 A196905 * A196907 A196908 A196909

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 07 2011

STATUS

approved

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Last modified December 5 03:03 EST 2021. Contains 349530 sequences. (Running on oeis4.)