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A215789 Number of permutations of 0..floor((3*n-1)/2) on even squares of an 3*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.

%I A215789 #5 Jul 22 2025 23:24:45
%S A215789 1,1,1,2,5,12,42,110,462,1274,6006,17136,87516,255816,1385670,4124406,
%T A215789 23371634,70549050,414315330,1264752060,7646001090,23555382240,
%U A215789 145862174640,452806924752,2861142656400,8939481277552,57468093927120
%N A215789 Number of permutations of 0..floor((3*n-1)/2) on even squares of an 3*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.
%C A215789 Row 3 of A215788
%e A215789 Some solutions for n=5
%e A215789 ..0..x..1..x..2....0..x..1..x..3....0..x..1..x..3....0..x..1..x..2
%e A215789 ..x..3..x..5..x....x..2..x..5..x....x..2..x..4..x....x..3..x..4..x
%e A215789 ..4..x..6..x..7....4..x..6..x..7....5..x..6..x..7....5..x..6..x..7
%K A215789 nonn
%O A215789 1,4
%A A215789 _R. H. Hardin_ Aug 23 2012