

A194090


The number of biconnected squaregraphs of perimeter 2*n.


5




OFFSET

1,4


COMMENTS

The CWEB program squaregraph.w cited below relates a(n) to the number of certain partitions of {1,2,...,2*n} into n pairs.


REFERENCES



LINKS



EXAMPLE

For n=4 the a(4)=3 cases of perimeter 8 are the two trominoes and the square tetromino.


PROG

(CWEB) (see Knuth link).


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



