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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 8 |
| 7 | 19 |
| 8 | 64 |
| 9 | 213 |
| 10 | 880 |
| 11 | 3717 |
| 12 | 18288 |
| 13 | 92935 |
| 14 | 531440 |
| 15 | 3147495 |
| 16 | 20525168 |
| 17 | 138638825 |
| 18 | 1015694832 |
| 19 | 7700244745 |
| 20 | 62623847536 |
| 21 | 526317901451 |
| 22 | 4705365925872 |
| 23 | 43407723925499 |
| 24 | 423149546210416 |
| 25 | 4250149857500861 |
| 26 | 44868038386273776 |
| 27 | 487341646372204813 |
[1,1,1,1,2,3,8,19,64,213,880,3717,18288,92935, 531440,3147495,20525168,138638825,1015694832, 7700244745,62623847536,526317901451,4705365925872, 43407723925499,423149546210416,4250149857500861, 44868038386273776,487341646372204813] |