A194093 The number of labeled biconnected squaregraphs with n vertices.

1, 1, 0, 1, 0, 3, 0, 12, 2, 55, 22, 278, 182, 1506, 1378, 8595, 10040, 51134, 71814, 314693, 509200

Offset

1,6

References

See A194088

Links

Table of n, a(n) for n=1..21.

Don Knuth, squaregraph.w (CWEB program).

Example

[See A194089 for the definition of "labeling".] For n=11 the P-pentomino can be labeled in 20 ways; the 5-cogwheel in only 2; hence a(11)=22.
The values of a(1) and a(2) depend on whether or not one believes that
the small complete graphs K_1 and K_2 respectively are biconnected.

Prog

(CWEB) (see Knuth link).

Crossrefs

Cf. A194088, A194089, A194090, A194091, A194092.

Sequence in context: A028851 A132221 A140093 * A055314 A110890 A249010

Adjacent sequences: A194090 A194091 A194092 * A194094 A194095 A194096

Keyword

nonn,hard,more

Author

Don Knuth, Aug 15 2011

Status

approved