A194088 The number of biconnected squaregraphs that contain n squares.

1, 1, 2, 6, 18, 72, 318, 1601, 8417

Offset: 1

Author

Don Knuth, Aug 15 2011

Keywords

• nonn
• more

Examples

			For n=5 the a(5)=18 solutions are the 12 pentominoes, plus the "5-cogwheel", plus five others obtained by "tearing" the P-pentomino or the 5-cogwheel apart at one edge.
		

References

• V. Chepoi, F. Dragan, Y. Vaxès, Center and diameter problem in planar quadrangulations and triangulations, SODA 13 (2002), 346--355.
• H.-J. Bandelt, V.Chepoi, and D. Eppstein, Combinatorics and geometry of finite and infinite squaregraphs, SIAM Journal on Discrete Mathematics 24 (2010), 1399--1440.

Links

• Don Knuth, squaregraph.w (CWEB program).

Crossrefs

Cf. A194089, A194090, A194091, A194092, A194093.

Programs

CWEB

@ See Knuth link.