A129114 - OEIS

%I #8 Jan 29 2025 22:33:04

%S 1,3,11,81,1228,28174,843186,30551755,1291861997,62352938720,

%T 3381736322813,203604398647922,13475238697911184,972429507963453210,

%U 75993857157285258473,6393779463050776636807,576237114190853665462712,55385308766655472416299110,5655262782600929403228668176

%N Number of unrooted unlabeled connected triangular maps on a compact closed oriented surface with 2n faces (and thus 3n edges).

%C 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.

%H Andrew Howroyd, <a href="/A129114/b129114.txt">Table of n, a(n) for n = 0..300</a>

%F Inverse Euler transform of A129115. - _Andrew Howroyd_, Jan 29 2025

%Y Column 3 of A380626.

%Y Connected version of A129115.

%Y Unrooted version of A062980.

%Y Cf. also A121350, A121352, A005133.

%K nonn,changed

%O 0,2

%A _Samuel A. Vidal_, Mar 30 2007

%E a(0)=1 prepended and terms a(17) onwards from _Andrew Howroyd_, Jan 29 2025