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A263226
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a(n) = 15*n^2 - 13*n.
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4
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0, 2, 34, 96, 188, 310, 462, 644, 856, 1098, 1370, 1672, 2004, 2366, 2758, 3180, 3632, 4114, 4626, 5168, 5740, 6342, 6974, 7636, 8328, 9050, 9802, 10584, 11396, 12238, 13110, 14012, 14944, 15906, 16898, 17920, 18972, 20054, 21166, 22308, 23480, 24682, 25914
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OFFSET
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0,2
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COMMENTS
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For n>=3, a(n) = the Wiener index of the Jahangir graph J_{3,n}. The Jahangir graph J_{3,n} is a connected graph consisting of a cycle graph C(3n) and one additional center vertex that is adjacent to n vertices of C(3n) at distances 3 to each other on C(3n).
The Hosoya polynomial of J_(3,n) is 4nx + (1/2)n(n+9)x^2 + 2n(n-1)x^3 + n(2n-5)x^4.
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LINKS
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FORMULA
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MAPLE
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seq(15*n^2-13*n, n = 0 .. 40);
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {0, 2, 34}, 50] (* Harvey P. Dale, Jul 27 2018 *)
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PROG
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(PARI) vector(50, n, n--; 15*n^2 - 13*n) \\ Altug Alkan, Oct 12 2015
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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