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A183985 1/4 the number of (n+1) X 9 binary arrays with all 2 X 2 subblock sums the same. 1
153, 155, 158, 164, 174, 194, 230, 302, 438, 710, 1238, 2294, 4374, 8534, 16790, 33302, 66198, 131990, 263318, 525974, 1050774, 2100374, 4198550, 8394902, 16785558, 33566870, 67125398, 134242454, 268468374, 536920214, 1073807510, 2147582102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 8 of A183986.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

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

Conjectures from Colin Barker, Apr 09 2018: (Start)

G.f.: x*(153 - 304*x - 307*x^2 + 608*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).

a(n) = 3*2^(n/2-1) + 2^(n-1) + 150 for n even.

a(n) = 2^(n-1) + 2^((n+1)/2) + 150 for n odd.

(End)

EXAMPLE

Some solutions for 5 X 9:

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

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

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

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

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

CROSSREFS

Cf. A183986.

Sequence in context: A095226 A346630 A165340 * A184045 A203603 A272767

Adjacent sequences: A183982 A183983 A183984 * A183986 A183987 A183988

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 08 2011

STATUS

approved

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Last modified January 28 02:32 EST 2023. Contains 359849 sequences. (Running on oeis4.)