A185554 1/3 the number of n X 4 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

3, 120, 2530, 58458, 1317540, 30132444, 684657326, 15594228288, 354894362166, 8078976180614, 183894888689408, 4185999926427220, 95284617951103300, 2168945067666040200, 49371181800142293644, 1123825227937533564738

Offset

1,1

Comments

Column 4 of A185559

Links

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

Robert Israel, Linear recurrence of order 101

Robert Israel, Maple-assisted derivation of recurrence

Formula

Linear recurrence of order 101: see link. - Robert Israel, Dec 22 2019

Example

Some solutions for 6 X 4 with a(1,1)=0:
  0 0 0 1     0 0 0 1     0 0 0 1     0 0 0 1     0 0 0 1
  0 1 0 1     0 1 0 1     0 1 0 1     0 1 0 1     0 1 0 1
  2 1 0 0     0 1 2 2     0 1 0 0     2 1 0 2     1 1 2 2
  2 1 2 2     0 2 1 2     0 2 2 1     2 1 2 2     2 0 1 1
  0 0 0 2     2 2 1 1     0 0 2 1     0 1 1 1     2 0 1 2
  1 1 1 2     0 0 0 1     1 1 1 1     0 0 2 2     0 0 1 2

Crossrefs

Sequence in context: A317433 A214312 A343831 * A134230 A321109 A307936

Adjacent sequences: A185551 A185552 A185553 * A185555 A185556 A185557

Keyword

nonn

Author

R. H. Hardin, Jan 31 2011

Status

approved