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A185479
Number of (n+1) X 2 binary arrays with every 2 X 2 subblock determinant equal to some horizontal or vertical neighbor 2 X 2 subblock determinant.
2
0, 30, 76, 234, 632, 1832, 5182, 14860, 42346, 121016, 345376, 986330, 2815960, 8040658, 22957720, 65550976, 187164486, 534405148, 1525866290, 4356753200, 12439678168, 35518569746, 101414891304, 289566302122, 826788250864
OFFSET
1,2
COMMENTS
Column 1 of A185487.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) - 5*a(n-3) + 3*a(n-4) - 2*a(n-6) for n>7.
Empirical g.f.: 2*x^2*(15 - 7*x - 12*x^2 + 2*x^3 - 4*x^4 - 2*x^5) / (1 - 3*x - x^2 + 5*x^3 - 3*x^4 + 2*x^6). - Colin Barker, Feb 27 2018
EXAMPLE
Some solutions for 3 X 2:
..1..1....1..0....1..0....1..1....0..1....0..0....0..1....1..1....1..1....1..0
..0..0....0..0....1..0....1..1....0..0....0..0....0..0....1..1....0..0....0..0
..1..1....1..0....0..0....0..0....0..1....0..0....1..1....1..1....1..0....1..1
CROSSREFS
Cf. A185487.
Sequence in context: A308137 A179321 A039517 * A045560 A159219 A098998
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 28 2011
STATUS
approved