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A215785 Number of permutations of 0..floor((n*7-1)/2) on even squares of an n X 7 array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing. 1
1, 5, 42, 262, 2465, 15485, 146205, 918637, 8674386, 54503318, 514658321, 3233726365, 30535100957, 191859642509, 1811672635826, 11383190276278, 107488026474001, 675374034791837, 6377352953765373, 40070496565665517 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A215788.

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 - 19*x^2 - 43*x^3 + 2*x^4 - 2*x^5) / (1 - 61*x^2 + 99*x^4 + 2*x^6). - Colin Barker, Jul 23 2018

EXAMPLE

Some solutions for n=4:

..0..x..1..x..2..x..3....0..x..1..x..3..x..4....0..x..1..x..2..x..6

..x..4..x..6..x..7..x....x..2..x..5..x..6..x....x..3..x..4..x..8..x

..5..x..8..x..9..x.12....7..x..8..x..9..x.10....5..x..7..x.10..x.12

..x.10..x.11..x.13..x....x.11..x.12..x.13..x....x..9..x.11..x.13..x

CROSSREFS

Cf. A215788.

Sequence in context: A266021 A062021 A241780 * A082145 A126765 A228793

Adjacent sequences:  A215782 A215783 A215784 * A215786 A215787 A215788

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 23 2012

STATUS

approved

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Last modified February 21 06:40 EST 2019. Contains 320371 sequences. (Running on oeis4.)