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A203916 Number of (n+2) X 3 0..1 arrays with every 3 X 3 subblock having equal diagonal elements or equal antidiagonal elements, and new values 0..1 introduced in row major order. 1
112, 392, 1400, 5000, 17800, 63368, 225704, 803912, 2863144, 10197128, 36317672, 129347528, 460677928, 1640728328, 5843540840, 20812080200, 74123322280, 263994125192, 940229020136, 3348675314888, 11926483984936, 42476802576392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A203923.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) +6*a(n-3) +4*a(n-4).

Empirical g.f.: 8*x*(14 + 7*x + 28*x^2 + 16*x^3) / ((1 + 2*x^2)*(1 - 3*x - 2*x^2)). - Colin Barker, Jun 05 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

CROSSREFS

Cf. A203923.

Sequence in context: A235319 A203923 A235312 * A234681 A234674 A217992

Adjacent sequences:  A203913 A203914 A203915 * A203917 A203918 A203919

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 07 2012

STATUS

approved

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Last modified January 20 19:53 EST 2020. Contains 331096 sequences. (Running on oeis4.)