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URL: https://oeis.org/A214816

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A214816
Number of unsensed combinatorial maps with n edges on an orientable surface of any genus.
13
1, 2, 5, 20, 96, 644, 5839, 67834, 970568, 16256556, 308620966, 6506035400, 150358570914, 3775903806928, 102348067516576, 2977979542305736, 92579723269733557, 3062602106878957610, 107418879166917701583, 3981908920500346885116, 155550644128029095714786
OFFSET
0,2
LINKS
Antonio Breda d'Azevedo, Alexander Mednykh, and Roman Nedela, Enumeration of maps regardless of genus: Geometric approach, Discrete Mathematics, Volume 310, 2010, Pages 1184-1203.
T. R. Walsh, Space-Efficient Generation of Nonisomorphic Maps and Hypermaps, J. Int. Seq. 18 (2015) # 15.4.3.
FORMULA
a(n) = (A170946(n) + A170947(n)) / 2. [Breda d'Azevedo, Mednykh & Nedela, Corollary 4.7] - Andrey Zabolotskiy, Jun 06 2024
CROSSREFS
Row sums of A379439.
Cf. A006385, A006387, A170946 (sensed), A170947 (achiral), A170948 (chiral pairs), A214814, A214815, A297880, A297881, A348798, A348800, A348801.
Sequence in context: A115082 A020105 A347071 * A020005 A259834 A074415
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 31 2012
EXTENSIONS
a(12)-a(18) from Andrey Zabolotskiy, Jun 06 2024
a(19) onwards from Andrew Howroyd, Jan 27 2025
STATUS
approved