cp's OEIS Frontend

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.

%I A215866 #11 Nov 27 2015 05:43:35
%S A215866 1,5,12,78,189,1233,2988,19494,47241,308205,746892,4872798,11808549,
%T A215866 77040153,186696108,1218024054,2951712081,19257264405,46667304972,
%U A215866 304462158318,737821743309,4813622739873,11665145978028,76104577363014
%N 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.
%C A215866 Column 6 of A215870.
%H A215866 R. H. Hardin, <a href="/A215866/b215866.txt">Table of n, a(n) for n = 1..210</a>
%F A215866 Empirical: a(n) = 16*a(n-2) -3*a(n-4).
%F A215866 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 A215866 Some solutions for n=4:
%e A215866 ..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 A215866 ..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 A215866 ..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 A215866 ..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 A215866 nonn
%O A215866 1,2
%A A215866 _R. H. Hardin_, Aug 25 2012