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A187462 T(n,k)=Number of (n+1)X(n+1) 0..k arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.

%I A187462 #7 Jul 22 2025 10:46:24
%S A187462 6,50,26,192,1236,144,512,13726,89618,1272,1126,84048,5098224,
%T A187462 11684688,15192,2146,325932,100936174,3387715318,6112320620,286392,
%U A187462 3760,1118854,1061948616,216668424092,19708386669940,4871877392202,7648032,6112
%N A187462 T(n,k)=Number of (n+1)X(n+1) 0..k arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.
%C A187462 Table starts
%C A187462 .........6................50................192..............512..........1126
%C A187462 ........26..............1236..............13726............84048........325932
%C A187462 .......144.............89618............5098224........100936174....1061948616
%C A187462 ......1272..........11684688.........3387715318.....216668424092.5212823523842
%C A187462 .....15192........6112320620.....19708386669940.7540469990506332
%C A187462 ....286392.....4871877392202.150657364854061134
%C A187462 ...7648032.17264863350746654
%C A187462 .314011868
%H A187462 R. H. Hardin, <a href="/A187462/b187462.txt">Table of n, a(n) for n = 1..40</a>
%e A187462 Some k=3 solutions for 4X4
%e A187462 ..0..2..2..0....0..2..3..3....0..2..2..3....0..2..2..2....0..2..2..0
%e A187462 ..3..2..0..2....1..2..0..1....3..2..0..1....2..2..0..2....2..3..0..3
%e A187462 ..2..0..1..2....3..0..2..3....2..0..3..3....2..0..1..1....2..0..1..0
%e A187462 ..0..2..2..3....2..1..3..0....1..1..2..0....3..2..2..0....2..3..3..3
%Y A187462 Row 1 is A062801
%K A187462 nonn,tabl
%O A187462 1,1
%A A187462 _R. H. Hardin_ Mar 10 2011