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A020874

Number of paths in Moebius ladder M_n.

0, 3, 30, 135, 452, 1295, 3378, 8295, 19560, 44847, 100790, 223223, 488940, 1061775, 2289882, 4910535, 10480208, 22275695, 47178270, 99605847, 209704980, 440390223, 922733570, 1929364775, 4026514872

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OFFSET

0,2

REFERENCES

J. P. McSorley, Counting structures in the Moebius ladder, Discrete Math., 184 (1998), 137-164.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,-26,44,-41,20,-4).

FORMULA

a(n) = 10*n*2^n-n^3-5*n^2-11*n.

G.f.: -x*(8*x^4-20*x^3+27*x^2-6*x-3) / ((x-1)^4*(2*x-1)^2). - Colin Barker, Apr 05 2013

MATHEMATICA

CoefficientList[Series[- x (8 x^4 - 20 x^3 + 27 x^2 - 6 x - 3)/((x - 1)^4 (2*x - 1)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 16 2013 *)

LinearRecurrence[{8, -26, 44, -41, 20, -4}, {0, 3, 30, 135, 452, 1295}, 30] (* Harvey P. Dale, Apr 05 2018 *)

PROG

(Magma) [10*n*2^n-n^3-5*n^2-11*n: n in [0..30]]; // Vincenzo Librandi, Oct 16 2013

CROSSREFS

Sequence in context: A365290 A221516 A174774 * A161806 A003689 A127868

Adjacent sequences: A020871 A020872 A020873 * A020875 A020876 A020877

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

URL: https://oeis.org/A020874

⇱ A020874 - OEIS