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A194088 The number of biconnected squaregraphs that contain n squares. 5
1, 1, 2, 6, 18, 72, 318, 1601, 8417 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

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

Table of n, a(n) for n=1..9.

Don Knuth, squaregraph.w (CWEB program).

EXAMPLE

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.

PROG

(CWEB) (see Knuth link).

CROSSREFS

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

Sequence in context: A264036 A261994 A177472 * A022491 A004395 A277862

Adjacent sequences:  A194085 A194086 A194087 * A194089 A194090 A194091

KEYWORD

nonn,more

AUTHOR

Don Knuth, Aug 15 2011

STATUS

approved

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Last modified April 23 10:51 EDT 2021. Contains 343204 sequences. (Running on oeis4.)