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A006433
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Number of tree-rooted planar maps with 4 vertices and n faces and no isthmuses.
(Formerly M3720)
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2
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0, 4, 175, 3324, 42469, 429120, 3711027, 28723640, 204598130, 1366223880, 8664086470, 52673351080, 309164754285, 1761471681568, 9783594370723, 53154274959360, 283267669144390, 1484104565936920, 7658877239935362, 38993558097982312, 196127054929939810
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listen;
history;
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OFFSET
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1,2
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COMMENTS
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A map without isthmuses can also be called bridgeless.
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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