A028456 Number of perfect matchings in graph P_{2} X C_{4} X P_{n}.

1, 9, 272, 6345, 155969, 3794880, 92524801, 2254970505, 54961579408, 1339585632201, 32649998822849, 795784687676160, 19395815427419969, 472737980834179401, 11522134787497383568, 280831232750814806025, 6844754271574955786881, 166828527501840135007680

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..500

Per Hakan Lundow, Computation of matching polynomials and the number of 1-factors in polygraphs, Research report, No 12, 1996, Department of Math., Umea University, Sweden.

Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.

Index entries for linear recurrences with constant coefficients, signature (24,27,-455,455,-27,-24,1).

Formula

G.f.: -(1+x)*(x^4-16*x^3+45*x^2-16*x+1) / ( (x-1)*(x^6-23*x^5-50*x^4+405*x^3-50*x^2-23*x+1) ). - R. J. Mathar, Dec 13 2013

Crossrefs

Sequence in context: A218693 A258302 A336195 * A180358 A220866 A197597

Adjacent sequences: A028453 A028454 A028455 * A028457 A028458 A028459

Keyword

nonn,easy

Author

Per H. Lundow

Status

approved