%I A045310
%S A045310 2,7,108,41025,13803794944,7174574164703330195841
%N A045310 Number of matchings in n-cube.
%C A045310 a(4)=A033532(0), a(5)=A033532(1).
%D A045310 Per Hakan Lundow, "Computation of matching polynomials and the number 
               of 1-factors in polygraphs", Research reports, No 12, 1996, Department 
               of Mathematics, Umea University.
%H A045310 Per Hakan Lundow, <a href="http://www.theophys.kth.se/~phl/Text/1factors2.ps.gz">
               Enumeration of matchings in polygraphs</a>, 1998.
%e A045310 Comment from Max Alekseyev, Nov 16 2009: E.g. for n=2, we have
%e A045310 1 matching of size 0 (i.e. the empty matching)
%e A045310 4 matchings of size 1 (i.e. an edge)
%e A045310 2 matchings of size 2 (that are the perfect matchings).
%e A045310 So a(2) = 1 + 4 + 2 = 7, whereas A005271(2) = 2.
%Y A045310 For perfect matchings see A005271.
%Y A045310 Cf. A033532.
%Y A045310 Sequence in context: A122524 A162634 A072664 this_sequence A000157 A034902 
               A101429
%Y A045310 Adjacent sequences: A045307 A045308 A045309 this_sequence A045311 A045312 
               A045313
%K A045310 nonn,new,hard,more
%O A045310 1,1
%A A045310 Per Hakan Lundow (phl(AT)theophys.kth.se)