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A192849
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Molecular topological indices of the triangular graphs.
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2
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0, 0, 24, 240, 1080, 3360, 8400, 18144, 35280, 63360, 106920, 171600, 264264, 393120, 567840, 799680, 1101600, 1488384, 1976760, 2585520, 3335640, 4250400, 5355504, 6679200, 8252400, 10108800, 12285000, 14820624, 17758440, 21144480
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OFFSET
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1,3
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COMMENTS
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Triangular graphs are defined for n>=2; extended to n=1 using closed form.
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LINKS
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FORMULA
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a(n) = n*(n^2 - 1)*(n-2)^2.
Sum_{n>=3} 1/a(n) = Pi^2/36 - 49/216.
Sum_{n>=3} (-1)^(n+1)/a(n) = Pi^2/72 - 10*log(2)/9 + 145/216. (End)
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MAPLE
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MATHEMATICA
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Table[n*(n^2-1)*(n-2)^2, {n, 1, 40}] (* G. C. Greubel, Jan 05 2019 *)
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PROG
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(Haskell)
a192849 n = if n < 3 then 0 else a245334 (n + 1) 4
(PARI) vector(40, n, n*(n^2 -1)*(n-2)^2) \\ G. C. Greubel, Jan 05 2019
(Magma) [n*(n^2 -1)*(n-2)^2: n in [1..40]]; // G. C. Greubel, Jan 05 2019
(Sage) [n*(n^2 -1)*(n-2)^2 for n in (1..40)] # G. C. Greubel, Jan 05 2019
(GAP) List([1..40], n -> n*(n^2 -1)*(n-2)^2); # G. C. Greubel, Jan 05 2019
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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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