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A295913
Number of n X 3 0..1 arrays with each 1 adjacent to 0 or 3 king-move neighboring 1's.
1
5, 13, 39, 115, 337, 993, 2919, 8587, 25257, 74289, 218511, 642715, 1890449, 5560465, 16355255, 48106475, 141497817, 416194129, 1224171199, 3600711835, 10590941633, 31151630513, 91627743527, 269508954923, 792719257161, 2331662118065
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-4).
Empirical g.f.: x*(5 + 3*x - 2*x^2 - 2*x^3) / (1 - 2*x - 3*x^2 + 2*x^4). - Colin Barker, Feb 22 2019
EXAMPLE
Some solutions for n=7:
..0..0..1. .1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..1
..0..0..0. .0..0..0. .0..1..1. .0..0..0. .0..0..0. .1..0..1. .0..1..1
..0..1..0. .0..0..0. .0..1..1. .1..0..1. .0..1..1. .0..0..0. .0..0..0
..0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..1. .0..0..0. .1..0..1
..0..0..0. .1..1..0. .0..0..0. .0..0..0. .0..0..0. .1..0..0. .0..0..0
..0..0..0. .1..1..0. .0..0..0. .1..0..0. .1..0..0. .0..0..0. .0..0..0
..1..0..0. .0..0..0. .0..0..1. .0..0..1. .0..0..1. .0..0..1. .0..0..0
CROSSREFS
Column 3 of A295918.
Sequence in context: A360797 A080143 A077919 * A272225 A272585 A026069
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 29 2017
STATUS
approved