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A200564
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a(n) = (2^(n^2)+2^((n^2+n)/2))/2.
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1
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1, 2, 12, 288, 33280, 16793600, 34360786944, 281475110928384, 9223372071214514176, 1208925819632221360750592, 633825300114132715146861084672, 1329227995784915909797295207699447808, 11150372599265311570918974863776009399828480
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OFFSET
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0,2
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COMMENTS
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The number of inequivalent n x n black and white checkerboards where two boards are indistinguishable if and only if they are identical after being reflected about the main diagonal.
Cycle index = (s_1^(n^2) + s_1^n*s_2^((n^2-n)/2))/2.
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LINKS
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MATHEMATICA
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Table[(2^(n^2)+2^((n^2+n)/2))/2, {n, 0, 10}]
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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