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A296330
Number of n X 3 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 0 or 2 neighboring 1s.
1
5, 19, 64, 230, 816, 2895, 10277, 36480, 129486, 459622, 1631463, 5790997, 20555577, 72963551, 258989554, 919302704, 3263133386, 11582734875, 41113779717, 145936421820, 518012193480, 1838722844160, 6526683619009, 23166949384421
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 4*a(n-2) + 5*a(n-3) + 2*a(n-4) - 2*a(n-5) - 3*a(n-6) - 2*a(n-7) + a(n-9).
Empirical g.f.: x*(5 + 9*x + 6*x^2 + x^3 - 5*x^4 - 5*x^5 - 2*x^6 + x^7 + x^8) / ((1 + x + x^2)*(1 - 3*x - 2*x^2 + 2*x^5 + x^6 - x^7)). - Colin Barker, Feb 23 2019
EXAMPLE
Some solutions for n=5:
..0..0..1. .0..0..1. .0..1..0. .0..0..1. .0..1..0. .1..0..0. .1..1..0
..1..0..0. .0..0..0. .0..0..0. .1..0..0. .0..0..0. .0..1..0. .1..0..0
..0..0..0. .0..0..1. .1..0..0. .0..0..1. .1..0..0. .0..0..0. .0..0..0
..1..0..0. .1..0..0. .0..0..1. .0..0..0. .0..0..0. .0..0..1. .1..0..0
..0..0..0. .0..0..1. .0..1..1. .1..0..0. .0..0..0. .0..0..0. .0..1..0
CROSSREFS
Column 3 of A296335.
Sequence in context: A304134 A318946 A229239 * A304162 A001870 A025568
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 10 2017
STATUS
approved