A378341 Number of connected achiral planar maps with an external face and n internal triangular faces.
1, 2, 6, 16, 45, 129, 367, 1081, 3098, 9291, 26788, 81341, 235729, 722479, 2102856, 6492146, 18965527, 58898531, 172600126, 538640825, 1582733185, 4959648919, 14607576158, 45935431662, 135571479679, 427621459608, 1264356405112, 3998682343629, 11842126315245, 37540318975749
Offset: 1