%I #25 Feb 16 2025 08:33:15
%S 24,72,180,336,600,936,1428,2016,2808,3720,4884,6192,7800,9576,11700,
%T 14016,16728,19656,23028,26640,30744,35112,40020,45216,51000,57096,
%U 63828,70896,78648,86760,95604,104832,114840,125256,136500,148176,160728,173736,187668
%N Molecular topological indices of the Moebius ladders.
%C Moebius ladders are defined for n>=3; extended to n=1 using closed form.
%H Colin Barker, <a href="/A192833/b192833.txt">Table of n, a(n) for n = 1..1000</a>
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MoebiusLadder.html">Moebius Ladder</a>
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MolecularTopologicalIndex.html">Molecular Topological Index</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) = (3/2)*n*(9 -(-1)^n +4*n +2*n^2).
%F G.f.: 12*x*(x^4+x^2+2*x+2)/((x-1)^4*(x+1)^2). - _Colin Barker_, Aug 07 2012
%F E.g.f.: (3/2)*x*(exp(-x) + (15 + 10*x + 2*x^2)*exp(x)). - _G. C. Greubel_, Jan 04 2019
%t Table[(3/2)*n*(9-(-1)^n+4*n+2*n^2), {n,1,40}] (* _G. C. Greubel_, Jan 04 2019 *)
%o (PARI) Vec(12*x*(x^4+x^2+2*x+2)/((x-1)^4*(x+1)^2) + O(x^40)) \\ _Colin Barker_, Aug 02 2015
%o (PARI) vector(40, n, (3/2)*n*(9-(-1)^n+4*n+2*n^2)) \\ _G. C. Greubel_, Jan 04 2019
%o (Magma) [(3/2)*n*(9-(-1)^n+4*n+2*n^2): n in [1..40]]; // _G. C. Greubel_, Jan 04 2019
%o (Sage) [(3/2)*n*(9-(-1)^n+4*n+2*n^2) for n in (1..40)] # _G. C. Greubel_, Jan 04 2019
%o (GAP) List([1..40], n -> (3/2)*n*(9-(-1)^n+4*n+2*n^2)); # _G. C. Greubel_, Jan 04 2019
%K nonn,easy,changed
%O 1,1
%A _Eric W. Weisstein_, Jul 11 2011
%E More terms from _Colin Barker_, Apr 05 2013