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, 55385308766655472416299110, 5655262782600929403228668176

Offset: 0

Author

Samuel A. Vidal, Mar 30 2007

Keywords

• nonn

Comments

Equivalently, the number of pairs 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

• Andrew Howroyd, Table of n, a(n) for n = 0..300

Crossrefs

Column 3 of A380626.

Connected version of A129115.

Unrooted version of A062980.

Cf. also A121350, A121352, A005133.

Formula

Inverse Euler transform of A129115. - Andrew Howroyd, Jan 29 2025

Extensions

a(0)=1 prepended and terms a(17) onwards from Andrew Howroyd, Jan 29 2025