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A060049
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Triangulations of an n-gon such that each internal vertex has valence at least 6, i.e., nonpositively curved triangulations.
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3
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1, 0, 1, 1, 2, 5, 15, 50, 181, 697, 2821, 11892, 51874, 232974, 1073070, 5053029, 24264565, 118570292, 588567257, 2963358162, 15114174106, 78004013763, 406971280545, 2144659072330, 11407141925639, 61197287846831
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OFFSET
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0,5
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COMMENTS
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This is the connected version of A059710 in the following sense. Let C(x) be the ordinary generating function for this sequence and A(x) the ordinary generating function for A059710. Then these satisfy the functional equation A(x) = C(x*A(x)). - Bruce Westbury, Nov 05 2013
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LINKS
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FORMULA
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The g.f. B(x) is derived from the g.f. A(x) of A059710 by A(x) = A(x*B(x))+1.
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EXAMPLE
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a(6) = 15 because there are 14 = A000108(4) triangulations without internal vertices, plus the triangulation with 6 pie slices.
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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