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A197607 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,2,1,1,1 for x=0,1,2,3,4. 2
1, 5, 14, 43, 124, 352, 1025, 2977, 8619, 24982, 72411, 209844, 608174, 1762633, 5108427, 14805217, 42908476, 124357153, 360411436, 1044543248, 3027291501, 8773685473, 25427864489, 73694947188, 213582435997, 619003863520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

Column 2 of A197613.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + a(n-2) + 4*a(n-3) + a(n-4) + 2*a(n-5) + 2*a(n-6) - a(n-7) - a(n-8).

Empirical g.f.: x*(1 + x)*(1 + 2*x + x^2 + 5*x^3 - 2*x^4 - x^6) / (1 - 2*x - x^2 - 4*x^3 - x^4 - 2*x^5 - 2*x^6 + x^7 + x^8). - Colin Barker, Mar 02 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A197613.

Sequence in context: A232492 A180774 A210972 * A296829 A102434 A186649

Adjacent sequences:  A197604 A197605 A197606 * A197608 A197609 A197610

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 16 2011

STATUS

approved

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Last modified January 24 16:44 EST 2021. Contains 340411 sequences. (Running on oeis4.)