

A211049


1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors


0



1, 4, 48, 1232, 69944, 8897744, 2543744944, 1632807480048, 2350761948259496, 7595900369159613200, 55087633557679363709984, 896577592582670794898595216
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