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A367119
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Place n points in general position on each side of an equilateral triangle, and join every pair of the 3*n+3 boundary points by a chord; sequence gives number of edges in the resulting planar graph.
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7
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3, 24, 153, 588, 1635, 3708, 7329, 13128, 21843, 34320, 51513, 74484, 104403, 142548, 190305, 249168, 320739, 406728, 508953, 629340, 769923, 932844, 1120353, 1334808, 1578675, 1854528, 2165049, 2513028, 2901363, 3333060, 3811233, 4339104, 4920003, 5557368, 6254745, 7015788
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OFFSET
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0,1
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COMMENTS
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"In general position" implies that the internal lines (or chords) only have simple intersections. There is no interior point where three or more chords meet.
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LINKS
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FORMULA
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Conjecture: a(n) = (3/2)*(3*n^4 + 4*n^3 + 3*n^2 + 4*n + 2).
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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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