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A145241
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1/4 of the number of 4-colorings of an n X n array symmetric about both diagonal and antidiagonal.
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0
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1, 3, 27, 189, 3969, 64827, 3179169, 121272795, 13891861179, 1237840901829, 331231632520635, 68946329439933309, 43098014529769439457, 20956433266778185286019, 30601694853748262964093129
(list; graph; refs; listen; history; internal format)
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