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A269869
Number of matchings (not necessarily perfect) in the triangle graph of order n.
8
1, 4, 27, 425, 14278, 1054396, 169858667, 59811185171, 46012925161519, 77344464552678876, 284066030784415134855, 2279568155737623235728996, 39969481180418160836567285156, 1531253921482570179838977438893104, 128176575381689893022287259560629125869
OFFSET
1,2
COMMENTS
The triangle graph of order n has n rows with i vertices in row i. Each vertex is connected to the neighbors in the same row and up to two vertices in each of the neighboring rows. The graph has A000217(n) vertices and 3*A000217(n-1) edges altogether.
LINKS
Eric Weisstein's World of Mathematics, Independent Edge Set
Eric Weisstein's World of Mathematics, Matching
Eric Weisstein's World of Mathematics, Triangular Grid Graph
CROSSREFS
Row sums of A288852.
Sequence in context: A271615 A271616 A123672 * A119030 A356806 A120093
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Mar 06 2016
STATUS
approved