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A197057 Number of n X 4 0..4 arrays with each element equal to the number its horizontal and vertical neighbors equal to 2. 1
1, 4, 10, 18, 28, 47, 93, 189, 357, 640, 1156, 2162, 4102, 7697, 14243, 26307, 48917, 91394, 170572, 317326, 589634, 1096821, 2042877, 3805343, 7083795, 13181280, 24530278, 45664276, 85014554, 158256855, 294565501, 548276423, 1020572419 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

Column 4 of A197061.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) +a(n-3) +2*a(n-4) +3*a(n-5) +2*a(n-6) -a(n-7) -3*a(n-8) -2*a(n-9).

Empirical g.f.: x*(1 + x)*(1 + x + x^2)*(1 + x + 2*x^2 - x^4 - 2*x^5) / (1 - x - x^3 - 2*x^4 - 3*x^5 - 2*x^6 + x^7 + 3*x^8 + 2*x^9). - Colin Barker, May 11 2018

EXAMPLE

Some solutions for n=5:

..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0

..0..1..1..1....0..0..0..0....1..1..1..0....1..1..1..1....1..1..0..0

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

..1..2..4..2....0..0..0..0....2..4..2..1....2..3..3..2....2..2..1..0

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

CROSSREFS

Cf. A197061.

Sequence in context: A217748 A009877 A009880 * A025712 A283969 A022781

Adjacent sequences:  A197054 A197055 A197056 * A197058 A197059 A197060

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 09 2011

STATUS

approved

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Last modified November 11 18:50 EST 2019. Contains 329031 sequences. (Running on oeis4.)