A183629 Number of (n+1) X 7 0..2 arrays with every 2 X 2 subblock summing to 4.

2445, 2967, 4029, 6207, 10725, 20247, 40749, 86127, 190005, 437127, 1049469, 2628447, 6849285, 18479607, 51306189, 145657167, 420452565, 1228323687, 3618906909, 10724596287, 31909543845, 95200145367, 284543467629

Offset

1,1

Comments

Column 6 of A183632.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3).

Conjectures from Colin Barker, Mar 31 2018: (Start)

G.f.: 3*x*(815 - 3901*x + 4374*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).

a(n) = 3*(644 + 21*2^(2+n) + 3^n).

(End)

Example

Some solutions for 3 X 7:
  1 1 0 1 1 0 1      2 0 1 1 2 1 1      0 2 1 2 0 1 1
  1 1 2 1 1 2 1      1 1 2 0 1 0 2      1 1 0 1 1 2 0
  1 1 0 1 1 0 1      2 0 1 1 2 1 1      0 2 1 2 0 1 1

Crossrefs

Cf. A183632.

Sequence in context: A259000 A256898 A255077 * A274684 A232141 A251338

Adjacent sequences: A183626 A183627 A183628 * A183630 A183631 A183632

Keyword

nonn

Author

R. H. Hardin, Jan 06 2011

Status

approved