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A341854
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Number of triangulations of a fixed hexagon with n internal nodes.
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4
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14, 84, 504, 3192, 21252, 147420, 1057224, 7791168, 58727214, 451137596, 3521923944, 27878644080, 223353322920, 1808402199660, 14778966163752, 121784464712064, 1011022286145816, 8449458780183120, 71042841567457760, 600615322603936920, 5103281457829103220
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OFFSET
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0,1
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COMMENTS
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These may be called rooted [n,3] triangulations.
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LINKS
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FORMULA
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a(n) = 1008*binomial(4*n+7, n)/((3*n+8)*(3*n+9)).
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MATHEMATICA
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Array[1008 Binomial[4 # + 7, #]/((3 # + 8) (3 # + 9)) &, 21, 0] (* Michael De Vlieger, Feb 22 2021 *)
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PROG
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(PARI) a(n) = {1008*binomial(4*n+7, n)/((3*n+8)*(3*n+9))}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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