OFFSET
1,1
COMMENTS
Moebius ladders are defined for n>=3; extended to n=1 using closed form.
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Moebius Ladder
Eric Weisstein's World of Mathematics, Molecular Topological Index
Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1).
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
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 11 2011
EXTENSIONS
More terms from Colin Barker, Apr 05 2013
STATUS
approved