A220240 Equals two maps: number of n X 4 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and vertical neighbors in a random 0..1 n X 4 array.

4, 78, 1131, 14976, 219617, 3101079, 43677639, 613533257

Offset

1,1

Comments

Column 4 of A220242.

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=3
..0..0..1..1....0..0..0..0....0..1..0..0....0..1..0..0....1..1..1..0
..0..0..0..0....1..0..1..1....0..1..0..1....1..0..1..0....0..1..1..0
..1..0..0..0....0..0..0..1....1..0..0..0....0..0..1..0....0..0..1..0

Crossrefs

Cf. A220242.

Sequence in context: A210519 A279437 A296997 * A246606 A210903 A054951

Adjacent sequences: A220237 A220238 A220239 * A220241 A220242 A220243

Keyword

nonn

Author

R. H. Hardin, Dec 08 2012

Status

approved