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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 16 |
| 3 | 110 |
| 4 | 828 |
| 5 | 6352 |
| 6 | 49696 |
| 7 | 393668 |
| 8 | 3148316 |
| 9 | 25362992 |
| 10 | 205519616 |
| 11 | 1673272702 |
| 12 | 13677016932 |
| 13 | 112165564656 |
| 14 | 922490228032 |
| 15 | 7605558361960 |
| 16 | 62839438825244 |
| 17 | 520180768020464 |
| 18 | 4313251202569216 |
| 19 | 35818392770702104 |
| 20 | 297846498752214128 |
| 21 | 2479748570715505472 |
[1,2,16,110,828,6352,49696,393668,3148316, 25362992,205519616,1673272702,13677016932, 112165564656,922490228032,7605558361960, 62839438825244,520180768020464,4313251202569216, 35818392770702104,297846498752214128, 2479748570715505472] |