A220373 Equals two maps: number of nX3 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and vertical neighbors in a random 0..2 nX3 array.

2, 23, 236, 2095, 18296, 154562, 1280878, 10492879, 85253117, 688997802, 5548695509, 44580367227, 357622113010, 2865892548630, 22950987106487, 183716756194773, 1470171909243331, 11762592622678971, 94098427741015878

Offset

1,1

Comments

Column 3 of A220375

Links

R. H. Hardin, Table of n, a(n) for n = 1..48

Example

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

Crossrefs

Sequence in context: A019518 A048677 A132933 * A220428 A110773 A088087

Adjacent sequences: A220370 A220371 A220372 * A220374 A220375 A220376

Keyword

nonn

Author

R. H. Hardin, Dec 13 2012

Status

approved