A220331 Equals two maps: number of 4 X n binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..1 4 X n array.

1, 37, 508, 6657, 92093, 1335202, 18836493, 265346645, 3750121527

Offset

1,2

Comments

Row 4 of A220328.

Links

Table of n, a(n) for n=1..9.

Example

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

Crossrefs

Cf. A220328.

Sequence in context: A197215 A264419 A197240 * A142764 A256811 A123035

Adjacent sequences: A220328 A220329 A220330 * A220332 A220333 A220334

Keyword

nonn

Author

R. H. Hardin, Dec 10 2012

Status

approved