

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
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OFFSET

1,2


LINKS



FORMULA

Empirical: a(n) = 4*a(n1) + 8*a(n2)  34*a(n3)  16*a(n4) + 60*a(n5)  25*a(n6).
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



KEYWORD

nonn


AUTHOR



STATUS

approved



