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%I #18 Sep 08 2022 08:45:58
%S 14,56,126,256,430,696,1022,1472,1998,2680,3454,4416,5486,6776,8190,
%T 9856,11662,13752,15998,18560,21294,24376,27646,31296,35150,39416,
%U 43902,48832,53998,59640
%N Molecular topological indices of the sunlet graphs.
%C Sunlet graphs are defined for n>=3; extended to n=1 using closed form.
%H G. C. Greubel, <a href="/A192846/b192846.txt">Table of n, a(n) for n = 1..1000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MolecularTopologicalIndex.html">Molecular Topological Index</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SunGraph.html">Sun Graph</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,-4,1,2,-1).
%F a(n) = n*(2*n*(n+3)+(-1)^n+7).
%F G.f.: 2*x*(x^4+2*x^3+14*x+7)/((x-1)^4*(x+1)^2). - _Colin Barker_, Aug 07 2012
%F E.g.f.: x*((15 + 12*x + 2*x^2)*exp(x) - exp(-x)). - _G. C. Greubel_, Jan 05 2019
%t Table[n*(2*n*(n+3)+(-1)^n+7), {n,1,40}] (* _G. C. Greubel_, Jan 05 2019 *)
%o (PARI) vector(40, n, n*(2*n*(n+3)+(-1)^n+7)) \\ _G. C. Greubel_, Jan 05 2019
%o (Magma) [n*(2*n*(n+3)+(-1)^n+7): n in [1..40]]; // _G. C. Greubel_, Jan 05 2019
%o (Sage) [n*(2*n*(n+3)+(-1)^n+7) for n in (1..40)] # _G. C. Greubel_, Jan 05 2019
%o (GAP) List([1..40], n -> n*(2*n*(n+3)+(-1)^n+7)); # _G. C. Greubel_, Jan 05 2019
%K nonn,easy
%O 1,1
%A _Eric W. Weisstein_, Jul 11 2011
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