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A129114
Number of unrooted unlabeled connected triangular maps on a compact closed oriented surface with 2n faces (and thus 3n edges).
1
3, 11, 81, 1228, 28174, 843186, 30551755, 1291861997, 62352938720, 3381736322813, 203604398647922, 13475238697911184, 972429507963453210, 75993857157285258473, 6393779463050776636807, 576237114190853665462712
OFFSET
1,1
COMMENTS
Equivalently, the number of pair of permutations (sigma,tau) up to simultaneous conjugacy on a set of size 6*n with sigma^3=tau^2=1, acting transitively and with no fixed point.
CROSSREFS
Connected version of A129115. Unrooted version of A062980.
Cf. also A121350, A121352, A005133.
Sequence in context: A163856 A232468 A099341 * A136649 A342058 A062580
KEYWORD
nonn
AUTHOR
Samuel A. Vidal, Mar 30 2007
STATUS
approved