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A000529
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Powers of rooted tree enumerator.
(Formerly M5086 N2202)
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1
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20, 74, 186, 388, 721, 1236, 1995, 3072, 4554, 6542, 9152, 12516, 16783, 22120, 28713, 36768, 46512, 58194, 72086, 88484, 107709, 130108, 156055, 185952, 220230, 259350, 303804, 354116, 410843, 474576, 545941, 625600, 714252, 812634, 921522, 1041732, 1174121, 1319588, 1479075, 1653568, 1844098, 2051742, 2277624, 2522916, 2788839, 3076664, 3387713, 3723360, 4085032, 4474210
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OFFSET
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1,1
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REFERENCES
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J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 150.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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MAPLE
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A000529:=(z-2)*(3*z**3-12*z**2+18*z-10)/(z-1)**6; [Conjectured by Simon Plouffe in his 1992 dissertation.]
a:= n-> (Matrix([[0, -3, 0, 3, 4, 4]]). Matrix(6, (i, j)-> if (i=j-1) then 1 elif j=1 then [6, -15, 20, -15, 6, -1][i] else 0 fi)^n)[1, 1]: seq(a(n), n=1..24); # Alois P. Heinz, Aug 26 2008
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MATHEMATICA
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a[n_] := ({0, -3, 0, 3, 4, 4}.MatrixPower[Table[If[i == j-1, 1, If[j == 1, {6, -15, 20, -15, 6, -1}[[i]], 0]], {i, 1, 6}, {j, 1, 6}], n])[[1]]; Table[a[n], {n, 1, 50}] (* Jean-François Alcover, Oct 14 2014, after Alois P. Heinz *)
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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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EXTENSIONS
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STATUS
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approved
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