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Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 9.
0

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

%S 1,0,0,4,4,0,0,1836,6871,0,0,294400160,3360660500,0,0,

%T 2033591738777760,62993444371397120,0

%N Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 9.

%K nonn

%O 1,4

%A _R. H. Hardin_ Feb 09 2009