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A197050 Number of nX4 0..4 arrays with each element equal to the number its horizontal and vertical zero neighbors. 4
3, 6, 18, 42, 108, 274, 692, 1754, 4442, 11248, 28488, 72146, 182712, 462728, 1171876, 2967826, 7516146, 19034954, 48206826, 122085820, 309187486, 783030352, 1983057390, 5022176478, 12718873752, 32211084212, 81575929322, 206594481604 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

Column 4 of A197054.

LINKS

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

FORMULA

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

Equivalent empirical G.f. 3*x -2*x^2*(1+x)*(x^4+3*x^3-3*x-3) ) / ( 1-x-3*x^2-3*x^3+x^4+2*x^5+x^6 ) . - R. J. Mathar, Oct 10 2011

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Sequence in context: A181037 A222856 A007990 * A121188 A120718 A032120

Adjacent sequences:  A197047 A197048 A197049 * A197051 A197052 A197053

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 09 2011

STATUS

approved

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Last modified December 6 19:31 EST 2019. Contains 329809 sequences. (Running on oeis4.)