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A059716
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Number of column convex polyominoes with n hexagonal cells.
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10
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1, 3, 11, 42, 162, 626, 2419, 9346, 36106, 139483, 538841, 2081612, 8041537, 31065506, 120010109, 463614741, 1791004361, 6918884013, 26728553546, 103255896932, 398891029862, 1540968200661, 5952961630324, 22997069087436
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: x(1-x)^3/(1-6x+10x^2-7x^3+x^4).
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MAPLE
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gf := x*(1-x)^3/(1-6*x+10*x^2-7*x^3+x^4): s := series(gf, x, 50): for i from 1 to 100 do printf(`%d, `, coeff(s, x, i)) od:
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MATHEMATICA
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a[1]=1; a[2]=3; a[3]=11; a[4]=42; a[n_] := a[n] = 6*a[n-1] - 10*a[n-2] + 7*a[n-3] - a[n-4]; Table[a[n], {n, 1, 24}] (* Jean-François Alcover, Mar 30 2015 *)
LinearRecurrence[{6, -10, 7, -1}, {1, 3, 11, 42}, 24] (* Ray Chandler, Jul 16 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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