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A252780
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Number of ways of n-coloring the square grid graph G_(4,4) such that no rectangle exists with sides parallel to the axes having all 4 corners of the same color.
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5
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0, 0, 840, 12477384, 2545607472, 116307115440, 2406303387000, 30037635498360, 262918567435104, 1765904422135392, 9653659287290280, 44745048366882600, 181129909217550480, 654743996230865424, 2149893215016113112, 6499426966335074520, 18286786291862020800
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OFFSET
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0,3
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COMMENTS
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The square grid graph G_(4,4) has 16 vertices, 24 edges and 36 rectangles with sides parallel to the axes.
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LINKS
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FORMULA
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a(n) = n *(n-1) *(n^14 +n^13 +n^12 -35*n^11 -35*n^10 +61*n^9 +547*n^8 -101*n^7 -1797*n^6 -633*n^5 +5655*n^4 -5625*n^3 +3684*n^2 -2436*n +852).
G.f.: -24 *x^2 *(1473*x^14 +32720*x^13 +4197221*x^12 +209614896*x^11 +3974036005*x^10 +33181507744*x^9 +132190513545*x^8 +263917493088*x^7 +267855509283*x^6 +135288479760*x^5 +31950100783*x^4 +3113672560*x^3 +97233591*x^2 +519296*x+35) / (x-1)^17.
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MAPLE
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a:= n-> ((((((((((((n^3-36)*n^2+96)*n+486)*n-648)*n-1696)*n
+1164)*n+6288)*n-11280)*n+9309)*n-6120)*n+3288)*n-852)*n:
seq(a(n), n=0..30);
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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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