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A209807 Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having two distinct values, and new values 0..3 introduced in row major order. 1
7, 34, 173, 930, 5193, 29782, 173789, 1025274, 6089457, 36315262, 217102757, 1299807138, 7788836985, 46697385574, 280057392749, 1679892321738, 10077743984769, 60460730002126, 362743958401973, 2176391017766514 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A209814.

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) - 7*a(n-2) - 28*a(n-3) - 12*a(n-4).

Empirical g.f.: x*(7 - 22*x - 50*x^2 - 20*x^3) / ((1 + x)*(1 - 6*x)*(1 - 3*x - 2*x^2)). - Colin Barker, Jul 13 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A209814.

Sequence in context: A055271 A209890 A027209 * A080048 A177140 A027233

Adjacent sequences:  A209804 A209805 A209806 * A209808 A209809 A209810

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 13 2012

STATUS

approved

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Last modified October 23 11:19 EDT 2019. Contains 328345 sequences. (Running on oeis4.)