| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 18 |
| 2 | 114 |
| 3 | 742 |
| 4 | 4874 |
| 5 | 32186 |
| 6 | 213226 |
| 7 | 1415510 |
| 8 | 9409592 |
| 9 | 62605198 |
| 10 | 416772336 |
| 11 | 2775553058 |
| 12 | 18488673878 |
| 13 | 123177305178 |
| 14 | 820730049614 |
| 15 | 5468888194572 |
| 16 | 36443213300730 |
| 17 | 242854735692378 |
| 18 | 1618394841578240 |
| 19 | 10785184848010492 |
[1,18,114,742,4874,32186,213226,1415510,9409592, 62605198,416772336,2775553058,18488673878, 123177305178,820730049614,5468888194572, 36443213300730,242854735692378,1618394841578240, 10785184848010492] |