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Search: id:A103944
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| A103944 |
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Number of rooted unicursal n-edge maps in the plane (planar with a distinguished outside face). |
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+0
2
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| 1, 10, 93, 836, 7355, 63750, 546553, 4646920, 39250935, 329789450, 2758868981, 22995369996, 191074697203, 1583463268366, 13092015636465, 108024564809744, 889730213085167, 7316434446188562, 60078376613838829, 492692533579612180
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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V. A. Liskovets and T. R. Walsh, Enumeration of unrooted maps on the plane, Rapport technique, UQAM, No. 2005-01, Montreal, Canada, 2005.
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LINKS
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V. A. Liskovets and T. R. Walsh, Counting unrooted maps on the plane, Advances in Applied Math., 36, No.4 (2006), 364-387.
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FORMULA
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a(n)=n*binomial(2n, n)sum_{i=0..n-2} binomial(n-2, i)(1/(n+1+i)+n/(n+2+i)).
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CROSSREFS
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Cf. A069720, A103945.
Adjacent sequences: A103941 A103942 A103943 this_sequence A103945 A103946 A103947
Sequence in context: A027325 A037534 A120996 this_sequence A099295 A050793 A126633
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KEYWORD
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easy,nonn
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AUTHOR
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Valery A. Liskovets (liskov(AT)im.bas-net.by), Mar 17 2005
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