cp's OEIS Frontend

A215871 Number of permutations of 0..floor((3*n-2)/2) on odd squares of an 3Xn array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.

%I A215871 #7 Jul 22 2025 23:25:58
%S A215871 1,1,1,2,4,12,29,110,290,1274,3532,17136,49100,255816,750325,4124406,
%T A215871 12310294,70549050,213446666,1264752060,3868253164,23555382240,
%U A215871 72686739116,452806924752
%N A215871 Number of permutations of 0..floor((3*n-2)/2) on odd squares of an 3Xn array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.
%C A215871 Row 3 of A215870
%e A215871 Some solutions for n=6
%e A215871 ..x..0..x..2..x..3....x..0..x..2..x..4....x..0..x..1..x..4....x..0..x..1..x..4
%e A215871 ..1..x..4..x..6..x....1..x..3..x..6..x....2..x..3..x..5..x....2..x..3..x..6..x
%e A215871 ..x..5..x..7..x..8....x..5..x..7..x..8....x..6..x..7..x..8....x..5..x..7..x..8
%K A215871 nonn
%O A215871 1,4
%A A215871 _R. H. Hardin_ Aug 25 2012