

A194092


The number of biconnected squaregraphs with n vertices.


5



1, 1, 0, 1, 0, 1, 0, 2, 1, 5, 2, 17, 11, 65, 54, 299, 333, 1508, 2041, 8215, 12971
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,8


REFERENCES

See A194088


LINKS

Table of n, a(n) for n=1..21.
Don Knuth, squaregraph.w (CWEB program).


EXAMPLE

For n=11 the a(11)=2 solutions are the P pentomino and the 5cogwheel.
The cases n=1 and n=2 are somewhat controversial, depending on whether the graphs K_1 and K_2 are considered to be "biconnected".


PROG

(CWEB) (see Knuth link).


CROSSREFS

Cf. A194088, A194089, A194090, A194091, A194093.
Sequence in context: A143891 A030400 A115345 * A140165 A185131 A199660
Adjacent sequences: A194089 A194090 A194091 * A194093 A194094 A194095


KEYWORD

nonn,hard,more


AUTHOR

Don Knuth, Aug 15 2011


STATUS

approved



