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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 17 |
| 4 | 74 |
| 5 | 365 |
| 6 | 1889 |
| 7 | 9938 |
| 8 | 52565 |
| 9 | 278513 |
| 10 | 1476506 |
| 11 | 7828925 |
| 12 | 41513921 |
| 13 | 220137122 |
| 14 | 1167334565 |
| 15 | 6190107857 |
| 16 | 32824743914 |
| 17 | 174062236685 |
| 18 | 923012961569 |
| 19 | 4894530600818 |
| 20 | 25954597551605 |
| 21 | 137631407453873 |
| 22 | 729828474212666 |
[1,2,5,17,74,365,1889,9938,52565,278513,1476506, 7828925,41513921,220137122,1167334565,6190107857, 32824743914,174062236685,923012961569, 4894530600818,25954597551605,137631407453873, 729828474212666] |