A263420 Number of n X 2 arrays of permutations of 0..n*2-1 with each element moved a city block distance of 0 or 2.

1, 4, 36, 196, 961, 5329, 29584, 160000, 868624, 4739329, 25816561, 140517316, 765186244, 4167218916, 22692108321, 123567013441, 672885527616, 3664192267264, 19953231345216, 108654793385121, 591677262389889

Offset

1,2

Comments

Column 2 of A263424.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 4*a(n-1) +4*a(n-2) +22*a(n-3) +14*a(n-4) -93*a(n-5) -68*a(n-6) +52*a(n-7) +32*a(n-8) +36*a(n-9) +45*a(n-10) -16*a(n-11) +8*a(n-12) -6*a(n-13) -2*a(n-14) +a(n-15).

Example

Some solutions for n=4
..0..5....3..5....0..5....3..1....0..5....3..2....0..1....0..5....4..1....3..2
..1..4....1..7....1..4....6..0....1..3....6..4....2..3....1..3....5..0....5..0
..7..2....0..6....7..6....4..2....7..6....0..1....4..5....4..2....3..6....4..1
..6..3....2..4....2..3....5..7....2..4....5..7....6..7....6..7....2..7....6..7

Crossrefs

Cf. A263424.

Sequence in context: A034569 A270084 A272222 * A302946 A220436 A144888

Adjacent sequences: A263417 A263418 A263419 * A263421 A263422 A263423

Keyword

nonn

Author

R. H. Hardin, Oct 17 2015

Status

approved