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A069725 Number of nonisomorphic unrooted unicursal planar maps with n edges and two vertices of valency 1 (unicursal means that exactly two vertices are of odd valency; there is an Eulerian path). 2
1, 1, 3, 11, 62, 342, 2152, 13768, 91800, 622616, 4301792, 30100448, 213019072, 1521473984, 10954616064, 79420280064, 579300888960, 4248201302400, 31302536066560, 231638727063040 (list; graph; refs; listen; history; internal format)
OFFSET

1,3

COMMENTS

There is an easy formula.

REFERENCES

V. A. Liskovets and T. R. S. Walsh, Enumeration of Eulerian and unicursal planar maps, Discr. Math., 282 (2004), 209-221.

CROSSREFS

Cf. A069727, A003645, A069732.

Sequence in context: A004108 A203007 A203768 * A193499 A199135 A096655

Adjacent sequences:  A069722 A069723 A069724 * A069726 A069727 A069728

KEYWORD

easy,nonn

AUTHOR

Valery A. Liskovets (liskov(AT)im.bas-net.by), Apr 07 2002

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Last modified February 16 15:27 EST 2012. Contains 205930 sequences.