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A071105
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Number of perfect matchings in variant of right triangle graph with n edges.
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1
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1, 0, 0, 3, 6, 0, 0, 1065, 6276, 0, 0, 45949563, 807343128, 0, 0, 221797080594801, 11812299253803024, 0, 0, 117066491250943949567763, 19100803250397148607852640, 0, 0, 6685924427990669481186818442889689, 3366736732994780307970181864980219968
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OFFSET
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0,4
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COMMENTS
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The graph consists of the vertices (x,y) where 0<=y<=x<n. Vertices (x1,y1) and (x2,y2) are adjacent iff x1=x2 and |y1-y2|=1 or |x1-x2|=1 and y1=y2 or |x1-x2|=|y1-y2|=1 and x1+y1 is even (all horizontal, all vertical and some diagonal). - Andrew Howroyd, Mar 06 2016
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REFERENCES
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J. Propp, Enumeration of matchings: problems and progress, pp. 255-291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 29).
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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