A380234 Triangle read by rows: T(n,k) is the number of achiral combinatorial maps with n edges and genus k, 0 <= k <= floor(n/2).
1, 2, 4, 1, 14, 6, 47, 34, 4, 184, 188, 46, 761, 1040, 408, 33, 3314, 5756, 3220, 538, 14997, 32069, 23824, 6489, 398, 69886, 179408, 169336, 66150, 8506, 333884, 1009234, 1170654, 611278, 129030, 6405, 1626998, 5700548, 7930892, 5279172, 1608172, 168702, 8067786, 32341002, 52930196, 43429578, 17758601, 3080190, 128448
Offset: 0
Examples
Triangle starts: n\k [0] [1] [2] [3] [4] [0] 1; [1] 2; [2] 4, 1; [3] 14, 6; [4] 47, 34, 4; [5] 184, 188, 46; [6] 761, 1040, 408, 33; [7] 3314, 5756, 3220, 538; [8] 14997, 32069, 23824, 6489, 398; [9] 69886, 179408, 169336, 66150, 8506; ...
Links
- Andrew Howroyd, Table of n, a(n) for n = 0..120 (rows 0..20)
- Evgeniy Krasko and Alexander Omelchenko, Enumeration of Unsensed Orientable Maps on Surfaces of a Given Genus, arXiv:1712.10139 [math.CO], 2017.
- Evgeniy Krasko, Reflexible maps with E edges on orientable surfaces of genus G, 2017 (data file).
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