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A297980
Number of n X 2 0..1 arrays with every element equal to 0, 2, 3 or 6 king-move adjacent elements, with upper left element zero.
2
1, 5, 6, 17, 24, 53, 94, 173, 340, 601, 1178, 2137, 4056, 7565, 14086, 26533, 49276, 92641, 172722, 323409, 604896, 1130389, 2116062, 3954141, 7399172, 13833769, 25873674, 48391369, 90490216, 169253917, 316506038, 591959445, 1107045516
OFFSET
1,2
COMMENTS
Column 2 of A297986.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-2) + 2*a(n-3) - 2*a(n-4) for n>5.
Empirical g.f.: x*(1 + 5*x + 3*x^2 - 2*x^4) / (1 - 3*x^2 - 2*x^3 + 2*x^4). - Colin Barker, Mar 22 2018
EXAMPLE
Some solutions for n=7:
..0..0. .0..0. .0..1. .0..1. .0..1. .0..0. .0..1. .0..0. .0..0. .0..0
..0..1. .0..0. .1..1. .1..1. .0..0. .0..1. .0..0. .0..0. .0..0. .0..1
..1..1. .1..1. .0..1. .0..0. .1..1. .1..1. .1..0. .1..1. .1..1. .1..1
..1..0. .0..1. .0..0. .0..1. .1..0. .0..1. .1..1. .1..0. .1..0. .0..1
..0..0. .0..0. .0..1. .1..1. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0
..0..1. .1..1. .1..1. .0..1. .1..1. .1..0. .0..1. .1..1. .1..0. .0..1
..1..1. .1..1. .0..1. .0..0. .0..1. .1..1. .1..1. .0..1. .1..1. .1..1
CROSSREFS
Cf. A297986.
Sequence in context: A041997 A041773 A041054 * A120034 A094425 A078981
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 10 2018
STATUS
approved