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A194089 The number of labeled biconnected squaregraphs that contain n squares 5
1, 3, 12, 57, 295, 1615, 9190, 53811, 322078 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

see A194088

LINKS

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

Don Knuth, squaregraph.w (CWEB program).

EXAMPLE

A biconnected squaregraph is "labeled" if one of the edges on its periphery is given an orientation. The a(2)=3 examples with n=2 are the domino together with two possible ways to orient one of the edges on its "long" side, and one way to orient an edge on the short side. If a squaregraph has m automorphisms and perimeter 2p, the number of different ways to label it is 4p/m.

PROG

(CWEB) (see Knuth link).

CROSSREFS

cf. A194088, A194090,  A194091,  A194092,  A194093.

Sequence in context: A165310 A133158 A328295 * A178807 A047891 A166991

Adjacent sequences:  A194086 A194087 A194088 * A194090 A194091 A194092

KEYWORD

nonn,hard,more

AUTHOR

Don Knuth, Aug 15 2011

STATUS

approved

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Last modified August 2 18:40 EDT 2021. Contains 346428 sequences. (Running on oeis4.)