

A204748


Number of (n+2) X 4 0..1 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..1 introduced in row major order.


1



61, 46, 31, 28, 38, 49, 70, 106, 159, 248, 394, 625, 1002, 1614, 2599, 4196, 6782, 10961, 17726, 28674, 46383, 75040, 121410, 196433, 317826, 514246, 832055, 1346284, 2178326, 3524593, 5702902, 9227482, 14930367, 24157832, 39088186, 63246001
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OFFSET

1,1


COMMENTS

Column 2 of A204754.


LINKS

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


FORMULA

Empirical: a(n) = a(n1) +a(n2) +a(n3) a(n4) a(n5) for n>8.
Empirical g.f.: x*(61  15*x  76*x^2  110*x^3  6*x^4 + 59*x^5 + 32*x^6 + 8*x^7) / ((1  x)*(1  x  x^2)*(1 + x + x^2)).  Colin Barker, Jun 09 2018


EXAMPLE

Some solutions for n=3:
..0..0..0..0....0..1..1..1....0..0..1..1....0..0..0..0....0..0..0..0
..0..0..0..0....0..0..1..1....0..0..1..1....1..1..1..1....1..1..1..1
..1..1..1..1....0..0..0..1....0..0..1..1....1..1..1..1....0..0..0..0
..0..0..0..0....1..0..0..0....0..0..1..1....0..0..0..0....1..1..1..1
..1..1..1..1....1..1..0..0....0..0..1..1....1..1..1..1....0..0..0..0


CROSSREFS

Cf. A204754.
Sequence in context: A199749 A303687 A033381 * A276471 A122568 A075028
Adjacent sequences: A204745 A204746 A204747 * A204749 A204750 A204751


KEYWORD

nonn


AUTHOR

R. H. Hardin, Jan 18 2012


STATUS

approved



