A183982 1/4 the number of (n+1) X 6 binary arrays with all 2 X 2 subblock sums the same.

25, 27, 30, 36, 46, 66, 102, 174, 310, 582, 1110, 2166, 4246, 8406, 16662, 33174, 66070, 131862, 263190, 525846, 1050646, 2100246, 4198422, 8394774, 16785430, 33566742, 67125270, 134242326, 268468246, 536920086, 1073807382, 2147581974, 4295098390

Offset

1,1

Comments

Column 5 of A183986.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).

Conjectures from Colin Barker, Apr 08 2018: (Start)

G.f.: x*(25 - 48*x - 51*x^2 + 96*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).

a(n) = 3*2^(n/2-1) + 2^(n-1) + 22 for n even.

a(n) = 2^(n-1) + 2^((n+1)/2) + 22 for n odd.

(End)

Example

Some solutions for 5 X 6:
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1
..1..0..0..1..0..1....1..1..0..1..1..1....1..0..1..1..0..1....1..0..1..0..0..0
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1
..1..0..0..1..0..1....1..1..0..1..1..1....1..0..1..1..0..1....1..0..1..0..0..0
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1

Crossrefs

Cf. A183986.

Sequence in context: A157091 A070662 A350181 * A287763 A239523 A361821

Adjacent sequences: A183979 A183980 A183981 * A183983 A183984 A183985

Keyword

nonn

Author

R. H. Hardin, Jan 08 2011

Status

approved