A183634 Number of (n+1) X 2 0..3 arrays with every 2 x 2 subblock summing to 6.

44, 136, 452, 1576, 5684, 21016, 79172, 302536, 1168724, 4552696, 17848292, 70313896, 278034164, 1102505176, 4381191812, 17438411656, 69494842004, 277203478456, 1106487293732, 4418971411816, 17654956552244, 70557047312536

Offset

1,1

Comments

Column 1 of A183642.

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 35*a(n-2) + 50*a(n-3) - 24*a(n-4).

Conjectures from Colin Barker, Feb 27 2018: (Start)

G.f.: 4*x*(11 - 76*x + 158*x^2 - 96*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)).

a(n) = 2 + 2^(2+n) + 2*3^(1+n) + 4^(1+n).

(End)

Example

Some solutions for 3 X 2:
..0..3....2..2....0..3....1..3....0..2....1..3....2..1....3..0....1..3....3..1
..3..0....0..2....0..3....0..2....1..3....1..1....2..1....0..3....2..0....1..1
..1..2....3..1....3..0....2..2....2..0....2..2....3..0....2..1....1..3....1..3

Crossrefs

Cf. A183642.

Sequence in context: A230829 A358818 A183642 * A043506 A044376 A102438

Adjacent sequences: A183631 A183632 A183633 * A183635 A183636 A183637

Keyword

nonn

Author

R. H. Hardin, Jan 06 2011

Status

approved