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 A192845 Molecular topological indices of the sun graphs. 1
 4, 56, 180, 400, 740, 1224, 1876, 2720, 3780, 5080, 6644, 8496, 10660, 13160, 16020, 19264, 22916, 27000, 31540, 36560, 42084, 48136, 54740, 61920, 69700, 78104, 87156, 96880, 107300, 118440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sun graphs are defined for n >= 3; extended to n=1 using closed form. LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 Eric Weisstein's World of Mathematics, Molecular Topological Index Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA a(n) = 4*n*(-3 + 3*n + n^2). a(n) = 4*A090197(n). G.f.: 4*x*(1 + 10*x - 5*x^2)/(1-x)^4. - Colin Barker, Aug 07 2012 E.g.f.: 4*x*(1 + 6*x + x^2)*exp(x). - G. C. Greubel, Jan 05 2019 MATHEMATICA Table[4*n*(-3+3*n+n^2), {n, 1, 40}] (* G. C. Greubel, Jan 05 2019 *) LinearRecurrence[{4, -6, 4, -1}, {4, 56, 180, 400}, 30] (* Harvey P. Dale, Mar 02 2024 *) PROG (PARI) vector(40, n, 4*n*(-3+3*n+n^2)) \\ G. C. Greubel, Jan 05 2019 (Magma) [4*n*(-3+3*n+n^2): n in [1..40]]; // G. C. Greubel, Jan 05 2019 (Sage) [4*n*(-3+3*n+n^2) for n in (1..40)] # G. C. Greubel, Jan 05 2019 (GAP) List([1..40], n -> 4*n*(-3+3*n+n^2)); # G. C. Greubel, Jan 05 2019 CROSSREFS Cf. A090197. Sequence in context: A168133 A189864 A360262 * A144138 A331776 A006592 Adjacent sequences: A192842 A192843 A192844 * A192846 A192847 A192848 KEYWORD nonn,easy AUTHOR Eric W. Weisstein, Jul 11 2011 STATUS approved

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Last modified May 22 04:07 EDT 2024. Contains 372742 sequences. (Running on oeis4.)