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.

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

R. H. Hardin, Table of n, a(n) for n = 1..200

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

Adjacent sequences: A185476 A185477 A185478 * A185480 A185481 A185482

Keyword

nonn

Author

R. H. Hardin, Jan 28 2011

Status

approved