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A046649
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Number of certain rooted planar maps.
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1
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2, 8, 34, 160, 806, 4256, 23256, 130416, 746350, 4341480, 25594530, 152585472, 918324904, 5572034240, 34048494608, 209347674768, 1294227005694, 8040125464280, 50165404177350, 314229490307040, 1975283452131990
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OFFSET
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2,1
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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.
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LINKS
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Table of n, a(n) for n=2..22.
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FORMULA
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a(n)=4(7n-11)(3n-5)!/[(n-2)!(2n-1)! ]. - Emeric Deutsch, Mar 03 2004
G.f.: 2*(g+1)/(1-g)^3 where g*(1-g)^2 = x. - Mark van Hoeij, Nov 10 2011
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CROSSREFS
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Sequence in context: A084207 A151305 A150901 * A174808 A109972 A019023
Adjacent sequences: A046646 A046647 A046648 * A046650 A046651 A046652
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KEYWORD
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nonn,easy
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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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