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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 87 |
| 6 | 669 |
| 7 | 6098 |
| 8 | 64050 |
| 9 | 759817 |
| 10 | 10028799 |
| 11 | 145575337 |
| 12 | 2302441248 |
| 13 | 39377544316 |
| 14 | 723627151168 |
| 15 | 14212023123570 |
| 16 | 296941929433826 |
| 17 | 6573946153123597 |
| 18 | 153673571064191583 |
| 19 | 3781352342496043197 |
| 20 | 97672909528404096334 |
| 21 | 2641852466110908004319 |
[1,1,3,14,87,669,6098,64050,759817,10028799, 145575337,2302441248,39377544316,723627151168, 14212023123570,296941929433826,6573946153123597, 153673571064191583,3781352342496043197, 97672909528404096334,2641852466110908004319] |