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Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 3.
0

%I #4 Dec 18 2015 18:17:16

%S 1,2,0,0,42,276,0,0,20340,216680,0,0,30693320,449345680,0,0,

%T 105796267920,1972495637280,0,0,696951215563680,15784392403940160,0,0,

%U 7817495632183997760,208339434598512497280,0,0

%N Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 3.

%K nonn

%O 3,2

%A _R. H. Hardin_ Feb 09 2009