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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. 2
1, 5, 12, 78, 189, 1233, 2988, 19494, 47241, 308205, 746892, 4872798, 11808549, 77040153, 186696108, 1218024054, 2951712081, 19257264405, 46667304972, 304462158318, 737821743309, 4813622739873, 11665145978028, 76104577363014 (list; graph; refs; listen; history; text; internal format)
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 A064371 A249478

Adjacent sequences:  A215863 A215864 A215865 * A215867 A215868 A215869

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 25 2012

STATUS

approved

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Last modified June 6 18:59 EDT 2020. Contains 334832 sequences. (Running on oeis4.)