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A204639 Number of (n+2) X 7 0..3 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically, diagonally or antidiagonally exactly three ways, and new values 0..3 introduced in row major order. 1
16855, 1860, 760, 1169, 3300, 3077, 9482, 35500, 109224, 410467, 1557742, 5832593, 22104912, 83813366, 317543288, 1203875773, 4564263072, 17303784013, 65603558830, 248722043144, 942974900136, 3575089065983, 13554191912090 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 5 of A204642.

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) -3*a(n-2) -4*a(n-3) -12*a(n-4) +12*a(n-5) +21*a(n-6) -9*a(n-7) -9*a(n-8) for n>10.

Empirical g.f.: x*(16855 - 82415*x + 42025*x^2 + 70369*x^3 + 209435*x^4 - 186816*x^5 - 358482*x^6 + 128064*x^7 + 150525*x^8 + 5130*x^9) / ((1 - x)*(1 - x - x^2)*(1 - 3*x - 3*x^2)*(1 - 3*x^3)). - Colin Barker, Jun 08 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

CROSSREFS

Cf. A204642.

Sequence in context: A203891 A088164 A234699 * A233986 A170797 A259426

Adjacent sequences:  A204636 A204637 A204638 * A204640 A204641 A204642

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 17 2012

STATUS

approved

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Last modified November 26 17:52 EST 2021. Contains 349343 sequences. (Running on oeis4.)