A215866 Number of permutations of 0..floor((n*6-2)/2) on odd squares of an n X 6 array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.

1, 5, 12, 78, 189, 1233, 2988, 19494, 47241, 308205, 746892, 4872798, 11808549, 77040153, 186696108, 1218024054, 2951712081, 19257264405, 46667304972, 304462158318, 737821743309, 4813622739873, 11665145978028, 76104577363014

Offset

1,2

Comments

Column 6 of A215870.

Links

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

Formula

Empirical: a(n) = 16*a(n-2) -3*a(n-4).

Empirical: g.f.: -x*(x-1)*(2*x^2+6*x+1) / ( 1-16*x^2+3*x^4 ). - R. J. Mathar, Nov 27 2015

Example

Some solutions for n=4:
..x..0..x..1..x..4....x..0..x..2..x..3....x..0..x..2..x..3....x..0..x..2..x..3
..2..x..3..x..5..x....1..x..4..x..6..x....1..x..4..x..7..x....1..x..4..x..6..x
..x..6..x..8..x.10....x..5..x..8..x..9....x..5..x..8..x..9....x..5..x..7..x..8
..7..x..9..x.11..x....7..x.10..x.11..x....6..x.10..x.11..x....9..x.10..x.11..x

Crossrefs

Sequence in context: A202203 A074245 A235939 * A219288 A377250 A368074

Adjacent sequences: A215863 A215864 A215865 * A215867 A215868 A215869

Keyword

nonn

Author

R. H. Hardin, Aug 25 2012

Status

approved