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A215867 Number of permutations of 0..floor((n*7-2)/2) on odd squares of an n X 7 array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing. 2
1, 5, 29, 262, 1642, 15485, 97289, 918637, 5772013, 54503318, 342457898, 3233726365, 20318307913, 191859642509, 1205501906765, 11383190276278, 71523418913482, 675374034791837, 4243543228336841, 40070496565665517 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A215870.

LINKS

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

FORMULA

Empirical: a(n) = 61*a(n-2) -99*a(n-4) -2*a(n-6).

Empirical: g.f.: -x*(-1 -5*x +32*x^2 +43*x^3 +28*x^4 +2*x^5) / ( 1 -61*x^2 +99*x^4 +2*x^6 ). - R. J. Mathar, Nov 27 2015

EXAMPLE

Some solutions for n=4:

..x..0..x..2..x..4..x....x..0..x..2..x..4..x....x..0..x..2..x..4..x

..1..x..3..x..5..x..7....1..x..3..x..5..x..8....1..x..3..x..6..x..8

..x..6..x..9..x.10..x....x..6..x..9..x.10..x....x..5..x..7..x.10..x

..8..x.11..x.12..x.13....7..x.11..x.12..x.13....9..x.11..x.12..x.13

CROSSREFS

Sequence in context: A103815 A134752 A231712 * A144015 A326986 A228387

Adjacent sequences:  A215864 A215865 A215866 * A215868 A215869 A215870

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 25 2012

STATUS

approved

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Last modified May 25 09:06 EDT 2020. Contains 334586 sequences. (Running on oeis4.)