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A066393
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Coordination sequence for (9^3, 3.9^2) net with respect to a vertex of type 9^3.
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2
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1, 3, 6, 6, 12, 15, 12, 21, 24, 18, 30, 33, 24, 39, 42, 30, 48, 51, 36, 57, 60, 42, 66, 69, 48, 75, 78, 54, 84, 87, 60, 93, 96, 66, 102, 105, 72, 111, 114, 78, 120, 123, 84, 129, 132, 90, 138, 141, 96, 147, 150, 102, 156, 159, 108, 165, 168, 114
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OFFSET
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0,2
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COMMENTS
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This net may be regarded as a tiling of the plane by 9-gons and triangles. There are two kinds of vertices: (a) 9^3 vertices, where three 9-gons meet, and (b) 3.9^2 vertices, where a triangle and two 9-gons meet. The present sequence is the coordination sequence with respect to a vertex of type 9^3. See also A319980.
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LINKS
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FORMULA
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G.f.: (1+3*x+6*x^2+4*x^3+6*x^4+3*x^5+x^6)/(1-x^3)^2.
a(n) = (1/2)*(3*n + lcm(n,3)), for n>=1. - Ridouane Oudra, Jan 22 2021
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MAPLE
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seq(coeftayl((1+3*x+6*x^2+4*x^3+6*x^4+3*x^5+x^6)/(1-x^3)^2, x = 0, k), k=0..60); # Muniru A Asiru, Feb 13 2018
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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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