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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 36 |
| 4 | 181 |
| 5 | 968 |
| 6 | 5411 |
| 7 | 31230 |
| 8 | 184701 |
| 9 | 1113534 |
| 10 | 6818157 |
| 11 | 42283904 |
| 12 | 265051573 |
| 13 | 1676628944 |
| 14 | 10689175724 |
| 15 | 68613428764 |
| 16 | 443067507573 |
| 17 | 2876254564034 |
| 18 | 18759923273027 |
| 19 | 122876716755094 |
| 20 | 807909302669408 |
| 21 | 5330342236103396 |
| 22 | 35278723624832375 |
[1,2,8,36,181,968,5411,31230,184701,1113534, 6818157,42283904,265051573,1676628944,10689175724, 68613428764,443067507573,2876254564034, 18759923273027,122876716755094,807909302669408, 5330342236103396,35278723624832375] |