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 A227438 Number of n X 2 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 3 binary array having two adjacent 1's and two adjacent 0's. 1

%I

%S 4,16,62,240,932,3620,14056,54576,211912,822832,3194960,12405648,

%T 48169664,187037120,726243040,2819915904,10949400256,42515227456,

%U 165081604736,640992365568,2488897617536,9664095367424,37524540428032

%N Number of n X 2 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 3 binary array having two adjacent 1's and two adjacent 0's.

%H R. H. Hardin, <a href="/A227438/b227438.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) + 6*a(n-3).

%F Empirical g.f.: 2*x*(2 + 3*x^2) / (1 - 4*x + 2*x^2 - 6*x^3). - _Colin Barker_, Sep 08 2018

%e Some solutions for n=4:

%e ..1..0....1..0....1..0....0..0....1..0....1..1....1..1....0..1....0..0....1..1

%e ..0..1....1..0....1..0....0..0....1..0....0..0....0..1....1..0....1..0....0..0

%e ..1..1....1..1....1..0....1..0....1..0....1..1....0..1....0..0....0..0....1..0

%e ..0..0....0..1....0..1....0..0....1..0....0..1....1..1....0..0....1..1....0..0

%Y Column 2 of A227442.

%K nonn

%O 1,1

%A _R. H. Hardin_ Jul 11 2013

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Last modified December 3 01:25 EST 2022. Contains 358510 sequences. (Running on oeis4.)