Number of rooted planar bi-Eulerian maps with 2n edges. Bi-Eulerian: all its vertices and faces are of even valency.
1, 1, 6, 54, 594, 7371, 99144, 1412802, 21025818, 323686935, 5120138790
2 seqfan posts
Tue Mar 27 03:34:13 CEST 2012 [seqfan] Re: Trouble with A069726