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A297852
Number of n X 2 0..1 arrays with every element equal to 1, 2 or 4 king-move adjacent elements, with upper left element zero.
6
1, 3, 7, 13, 23, 49, 95, 177, 359, 705, 1351, 2689, 5303, 10321, 20423, 40353, 79223, 156657, 309991, 611713, 1210967, 2399761, 4750919, 9419937, 18694199, 37092657, 73659175, 146373313, 290909975, 578470225, 1150862855, 2290191585, 4559123447
OFFSET
1,2
COMMENTS
Column 2 of A297858.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 4*a(n-3) - 10*a(n-4) + 4*a(n-5) for n>6.
Empirical g.f.: x*(1 - 6*x^3 - 4*x^4 + 4*x^5) / ((1 - 2*x)*(1 - x - 4*x^3 + 2*x^4)). - Colin Barker, Feb 19 2018
EXAMPLE
Some solutions for n=7:
..0..1. .0..1. .0..1. .0..0. .0..1. .0..1. .0..0. .0..0. .0..1. .0..0
..0..1. .1..0. .0..1. .1..0. .0..1. .0..1. .1..1. .1..1. .0..1. .0..1
..0..1. .1..0. .1..0. .1..1. .0..1. .0..1. .0..1. .1..0. .1..0. .1..1
..1..0. .0..1. .0..1. .1..1. .1..0. .0..1. .0..0. .0..0. .1..0. .0..0
..1..0. .0..1. .0..1. .1..0. .1..0. .1..0. .0..0. .0..0. .1..0. .1..1
..0..1. .0..1. .0..1. .0..0. .0..1. .1..0. .1..0. .0..1. .0..1. .0..1
..1..0. .1..0. .0..1. .1..1. .0..1. .1..0. .1..1. .1..1. .0..1. .0..0
CROSSREFS
Cf. A297858.
Sequence in context: A049112 A349793 A100720 * A297953 A084898 A147380
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 07 2018
STATUS
approved