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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

%I #11 Nov 27 2015 05:43:35

%S 1,5,12,78,189,1233,2988,19494,47241,308205,746892,4872798,11808549,

%T 77040153,186696108,1218024054,2951712081,19257264405,46667304972,

%U 304462158318,737821743309,4813622739873,11665145978028,76104577363014

%N 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.

%C Column 6 of A215870.

%H R. H. Hardin, <a href="/A215866/b215866.txt">Table of n, a(n) for n = 1..210</a>

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

%F 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

%e Some solutions for n=4:

%e ..x..0..x..1..x..4....x..0..x..2..x..3....x..0..x..2..x..3....x..0..x..2..x..3

%e ..2..x..3..x..5..x....1..x..4..x..6..x....1..x..4..x..7..x....1..x..4..x..6..x

%e ..x..6..x..8..x.10....x..5..x..8..x..9....x..5..x..8..x..9....x..5..x..7..x..8

%e ..7..x..9..x.11..x....7..x.10..x.11..x....6..x.10..x.11..x....9..x.10..x.11..x

%K nonn

%O 1,2

%A _R. H. Hardin_, Aug 25 2012

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Last modified March 5 06:19 EST 2024. Contains 370537 sequences. (Running on oeis4.)