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A192833
Molecular topological indices of the Moebius ladders.
1
24, 72, 180, 336, 600, 936, 1428, 2016, 2808, 3720, 4884, 6192, 7800, 9576, 11700, 14016, 16728, 19656, 23028, 26640, 30744, 35112, 40020, 45216, 51000, 57096, 63828, 70896, 78648, 86760, 95604, 104832, 114840, 125256, 136500, 148176, 160728, 173736, 187668
OFFSET
1,1
COMMENTS
Moebius ladders are defined for n>=3; extended to n=1 using closed form.
LINKS
Eric Weisstein's World of Mathematics, Moebius Ladder
Eric Weisstein's World of Mathematics, Molecular Topological Index
FORMULA
a(n) = (3/2)*n*(9 -(-1)^n +4*n +2*n^2).
G.f.: 12*x*(x^4+x^2+2*x+2)/((x-1)^4*(x+1)^2). - Colin Barker, Aug 07 2012
E.g.f.: (3/2)*x*(exp(-x) + (15 + 10*x + 2*x^2)*exp(x)). - G. C. Greubel, Jan 04 2019
MATHEMATICA
Table[(3/2)*n*(9-(-1)^n+4*n+2*n^2), {n, 1, 40}] (* G. C. Greubel, Jan 04 2019 *)
PROG
(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
(PARI) vector(40, n, (3/2)*n*(9-(-1)^n+4*n+2*n^2)) \\ G. C. Greubel, Jan 04 2019
(Magma) [(3/2)*n*(9-(-1)^n+4*n+2*n^2): n in [1..40]]; // G. C. Greubel, Jan 04 2019
(Sage) [(3/2)*n*(9-(-1)^n+4*n+2*n^2) for n in (1..40)] # G. C. Greubel, Jan 04 2019
(GAP) List([1..40], n -> (3/2)*n*(9-(-1)^n+4*n+2*n^2)); # G. C. Greubel, Jan 04 2019
CROSSREFS
Sequence in context: A304374 A064200 A305065 * A292353 A189540 A329077
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 11 2011
EXTENSIONS
More terms from Colin Barker, Apr 05 2013
STATUS
approved