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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 44 |
| 4 | 272 |
| 5 | 1808 |
| 6 | 12616 |
| 7 | 91136 |
| 8 | 675712 |
| 9 | 5112576 |
| 10 | 39316480 |
| 11 | 306402304 |
| 12 | 2414543328 |
| 13 | 19207303168 |
| 14 | 154030314752 |
| 15 | 1243912552448 |
| 16 | 10107398806016 |
| 17 | 82573989969920 |
| 18 | 677862373390592 |
| 19 | 5588755066388480 |
| 20 | 46257005500080128 |
| 21 | 384210240316375040 |
| 22 | 3201482490107076608 |
[1,2,8,44,272,1808,12616,91136,675712,5112576, 39316480,306402304,2414543328,19207303168, 154030314752,1243912552448,10107398806016, 82573989969920,677862373390592,5588755066388480, 46257005500080128,384210240316375040, 3201482490107076608] |