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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 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=1..16.

CROSSREFS

Connected version of A129115. Unrooted version of A062980.

Cf. also A121350, A121352, A005133.

Sequence in context: A163856 A232468 A099341 * A136649 A062580 A097495

Adjacent sequences:  A129111 A129112 A129113 * A129115 A129116 A129117

KEYWORD

nonn

AUTHOR

Samuel A. Vidal, Mar 30 2007

STATUS

approved

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Last modified April 9 09:56 EDT 2020. Contains 333346 sequences. (Running on oeis4.)