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A185790 Number of (n+1) X 2 binary arrays with no 2 X 2 subblock sum equal to any horizontal or vertical neighbor 2 X 2 subblock sum. 1
16, 40, 100, 260, 676, 1716, 4356, 11220, 28900, 73780, 188356, 483476, 1240996, 3174900, 8122500, 20822100, 53377636, 136666036, 349914436, 896578580, 2297284900, 5883599220, 15068544516, 38602941396, 98893896676, 253305662260 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A185798.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 4*a(n-3) + 16*a(n-4).

Empirical g.f.: 4*x*(4 + 6*x + 15*x^2 + 24*x^3) / ((1 + 4*x^2)*(1 - x - 4*x^2)). - Colin Barker, Apr 16 2018

EXAMPLE

Some solutions for 3 X 2:

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

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

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

CROSSREFS

Cf. A185798.

Sequence in context: A350284 A182461 A205065 * A185761 A205248 A205186

Adjacent sequences: A185787 A185788 A185789 * A185791 A185792 A185793

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 04 2011

STATUS

approved

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Last modified January 28 17:08 EST 2023. Contains 359895 sequences. (Running on oeis4.)