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A196630 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 1,3,2,0,4 for x=0,1,2,3,4. 3
1, 2, 5, 10, 26, 65, 161, 403, 1006, 2511, 6270, 15654, 39083, 97579, 243625, 608258, 1518637, 3791578, 9466426, 23634809, 59008985, 147327627, 367832622, 918367047, 2292885358, 5724642758, 14292705299, 35684571667, 89093606033, 222439846274 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Every 0 is next to 0 1's, every 1 is next to 1 3'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 A196636.

LINKS

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

FORMULA

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

Empirical g.f.: x*(1 - 3*x^3) / (1 - 2*x - x^2 - x^3 + x^4). - Colin Barker, Feb 22 2018

EXAMPLE

All solutions for n=4:

..0..0....0..0....0..0....0..0....0..0....0..0....2..2....0..0....0..0....0..0

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

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

..0..0....0..0....0..0....0..0....2..2....0..0....0..0....0..0....0..0....0..0

CROSSREFS

Cf. A196636.

Sequence in context: A264867 A115725 A305577 * A079572 A053391 A183956

Adjacent sequences:  A196627 A196628 A196629 * A196631 A196632 A196633

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 04 2011

STATUS

approved

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Last modified July 4 15:25 EDT 2020. Contains 335448 sequences. (Running on oeis4.)