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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 53 |
| 4 | 352 |
| 5 | 2345 |
| 6 | 15624 |
| 7 | 104093 |
| 8 | 693504 |
| 9 | 4620369 |
| 10 | 30782536 |
| 11 | 205084165 |
| 12 | 1366343392 |
| 13 | 9103063929 |
| 14 | 60647838152 |
| 15 | 404057392237 |
| 16 | 2691973550848 |
| 17 | 17934881869985 |
| 18 | 119488539398536 |
| 19 | 796074997934037 |
| 20 | 5303733776692576 |
[1,8,53,352,2345,15624,104093,693504,4620369, 30782536,205084165,1366343392,9103063929, 60647838152,404057392237,2691973550848, 17934881869985,119488539398536,796074997934037, 5303733776692576] |