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A290819
Number of rooted 4-regular one-face maps on genus g surface.
1
1, 45, 9450, 4729725, 4341887550, 6352181485650, 13566444744352500, 39834473380605028125, 153946961458244898693750, 757572997336023146471943750, 4625189759553876588251163487500, 34307345041490879593353005168531250, 303883906271359598859584503473567187500, 3168250194798584983481619521143486701562500, 38405528861348447169764191835301345796340625000
OFFSET
1,2
LINKS
Evgeniy Krasko, Alexander Omelchenko, Enumeration of 4-regular one-face maps, European Journal of Combinatorics, Volume 62, 2017, Pages 167-177.
FORMULA
a(g) = 2*((4g-2)!)/((4^g)*(g!)*((g-1)!)).
EXAMPLE
On a torus (g=1) there exists only one 4-regular one-face map.
CROSSREFS
Sequence in context: A364172 A209275 A199355 * A163035 A358707 A184136
KEYWORD
nonn
AUTHOR
Evgeniy Krasko, Sep 03 2017
STATUS
approved