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%I #12 Dec 13 2013 07:40:26
%S 1,9,272,6345,155969,3794880,92524801,2254970505,54961579408,
%T 1339585632201,32649998822849,795784687676160,19395815427419969,
%U 472737980834179401,11522134787497383568,280831232750814806025,6844754271574955786881,166828527501840135007680
%N Number of perfect matchings in graph P_{2} X C_{4} X P_{n}.
%H Alois P. Heinz, <a href="/A028456/b028456.txt">Table of n, a(n) for n = 0..500</a>
%H Per Hakan Lundow, <a href="http://www.theophys.kth.se/~phl/Text/1factors.pdf">Computation of matching polynomials and the number of 1-factors in polygraphs</a>, Research report, No 12, 1996, Department of Math., Umea University, Sweden.
%H Per Hakan Lundow, <a href="http://www.theophys.kth.se/~phl/Text/1factors2.ps.gz">Enumeration of matchings in polygraphs</a>, 1998.
%F 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
%K nonn
%O 0,2
%A _Per H. Lundow_