A194092 The number of biconnected squaregraphs with n vertices.

1, 1, 0, 1, 0, 1, 0, 2, 1, 5, 2, 17, 11, 65, 54, 299, 333, 1508, 2041, 8215, 12971

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 5-cogwheel.
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