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A194092 The number of biconnected squaregraphs with n vertices. 5
1, 1, 0, 1, 0, 1, 0, 2, 1, 5, 2, 17, 11, 65, 54, 299, 333, 1508, 2041, 8215, 12971 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 14 00:35 EDT 2021. Contains 345016 sequences. (Running on oeis4.)