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A269013 Number of 3 X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once. 1
0, 15, 46, 305, 1078, 4948, 18210, 73277, 270458, 1026795, 3757996, 13847240, 50155940, 181596651, 651546278, 2331910405, 8300115170, 29460799452, 104176325510, 367430075801, 1292287850546, 4534933300095, 15878737307224 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) + 8*a(n-2) - 34*a(n-3) - 16*a(n-4) + 60*a(n-5) - 25*a(n-6).
Empirical g.f.: x^2*(15 - 14*x + x^2) / (1 - 2*x - 6*x^2 + 5*x^3)^2. - Colin Barker, Jan 18 2019
EXAMPLE
Some solutions for n=4:
..1..1..0..1. .0..0..0..0. .1..0..0..0. .1..0..0..0. .0..1..0..1
..0..0..0..0. .1..1..0..0. .0..0..0..0. .1..0..1..0. .1..0..0..0
..1..0..0..0. .0..0..0..1. .1..1..0..0. .1..0..0..1. .0..0..0..0
CROSSREFS
Row 3 of A269011.
Sequence in context: A041436 A219885 A042007 * A041438 A045111 A031451
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 17 2016
STATUS
approved

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Last modified May 26 05:37 EDT 2024. Contains 372807 sequences. (Running on oeis4.)