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A000259
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Number of certain rooted planar maps.
(Formerly M2943 N1185)
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1
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1, 3, 13, 63, 326, 1761, 9808, 55895, 324301, 1908878, 11369744, 68395917, 414927215, 2535523154, 15592255913, 96419104103, 599176447614, 3739845108057, 23435007764606, 147374772979438, 929790132901804
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OFFSET
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1,2
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REFERENCES
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W. G. Brown, Enumeration of non-separable planar maps, Canad. J. Math., 15 (1963), 526-545.
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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Table of n, a(n) for n=1..21.
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MAPLE
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with(linalg): T := proc(n, k) if k<=n then k*sum((2*j-k)*(j-1)!*(3*n-j-k-1)!/(j-k)!/(j-k)!/(2*k-j)!/(n-j)!, j=k..min(n, 2*k))/(2*n-k)! else 0 fi end: A := matrix(30, 30, T): seq(sum(A[i, j], j=1..i), i=1..30); (from E. Deutsch)
R := RootOf(x-t*(t-1)^2, t); ogf := series(1/((1-R-R^2)*(R-1)^2), x=0, 30); - Mark van Hoeij, Nov 08 2011
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CROSSREFS
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Row sums of A046651.
Sequence in context: A026715 A001850 A130525 * A007855 A193112 A192729
Adjacent sequences: A000256 A000257 A000258 * A000260 A000261 A000262
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Emeric Deutsch, Mar 03 2004
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STATUS
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approved
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