

A363771


Number of graphs (with n vertices) admitting a strictly matched involution.


1



1, 1, 1, 2, 4, 9, 21, 65, 240, 1128, 6764, 53971
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OFFSET

0,4


LINKS



EXAMPLE

For n=0 the a(0)=1 solution is the empty graph K0.
For n=1 the a(1)=1 solution is the complete graph K1.
For n=2 the a(2)=1 solution is the complete graph K2.
For n=3 the a(3)=2 solutions are the complete graph K3 and the union of K1 and K2.
For n=4 the a(4)=4 solutions are the complete graph K4, the 4cycle C4, the paw (3pan), and the 2K2 (union of two K2).


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



