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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 67 |
| 5 | 471 |
| 6 | 3591 |
| 7 | 33573 |
| 8 | 329043 |
| 9 | 3919387 |
| 10 | 47827093 |
| 11 | 663429603 |
| 12 | 9764977399 |
| 13 | 156308277139 |
| 14 | 2653548775671 |
| 15 | 48880554540093 |
| 16 | 934560430625523 |
| 17 | 19120475459863299 |
| 18 | 413057291727064689 |
| 19 | 9325822483756554831 |
| 20 | 221409989926026560757 |
| 21 | 5513060361601128645777 |
[1,1,3,13,67,471,3591,33573,329043,3919387, 47827093,663429603,9764977399,156308277139, 2653548775671,48880554540093,934560430625523, 19120475459863299,413057291727064689, 9325822483756554831,221409989926026560757, 5513060361601128645777] |