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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 28 |
| 5 | 122 |
| 6 | 558 |
| 7 | 2641 |
| 8 | 12822 |
| 9 | 63501 |
| 10 | 319554 |
| 11 | 1629321 |
| 12 | 8399092 |
| 13 | 43701735 |
| 14 | 229211236 |
| 15 | 1210561517 |
| 16 | 6432491192 |
| 17 | 34364148528 |
| 18 | 184463064936 |
| 19 | 994430028087 |
| 20 | 5381653402890 |
| 21 | 29226425965907 |
| 22 | 159227245772460 |
| 23 | 870004781620093 |
| 24 | 4766330416567254 |
| 25 | 26176585256712224 |
[1,2,7,28,122,558,2641,12822,63501,319554,1629321, 8399092,43701735,229211236,1210561517,6432491192, 34364148528,184463064936,994430028087, 5381653402890,29226425965907,159227245772460, 870004781620093,4766330416567254, 26176585256712224] |