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A228663 Number of 4 X n binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally. 1
8, 12, 140, 416, 2844, 11148, 62368, 275708, 1420076, 6614240, 32897116, 156718796, 767930400, 3694025404, 17985757548, 86879470432, 421850136604, 2041379040012, 9900460336800, 47946203889788, 232416817429420, 1125924852017632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 16*a(n-2) - 7*a(n-3) - 18*a(n-4).

Empirical g.f.: 4*x*(1 + x)*(2 - 3*x) / (1 - 2*x - 16*x^2 + 7*x^3 + 18*x^4). - Colin Barker, Sep 12 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Row 4 of A228660.

Sequence in context: A196077 A067923 A258780 * A076028 A281256 A070476

Adjacent sequences:  A228660 A228661 A228662 * A228664 A228665 A228666

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 29 2013

STATUS

approved

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Last modified January 28 22:30 EST 2022. Contains 350669 sequences. (Running on oeis4.)