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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 11 |
| 4 | 47 |
| 5 | 296 |
| 6 | 2638 |
| 7 | 31184 |
| 8 | 460445 |
| 9 | 8121616 |
| 10 | 166019736 |
| 11 | 3851820576 |
| 12 | 99905492939 |
| 13 | 2863509479104 |
| 14 | 89861971946594 |
| 15 | 3064181181957632 |
| 16 | 112806282518694969 |
| 17 | 4459192457431503104 |
| 18 | 188376562263115020076 |
| 19 | 8469292812455408254464 |
| 20 | 403767081039021522624615 |
[1,2,4,11,47,296,2638,31184,460445,8121616, 166019736,3851820576,99905492939,2863509479104, 89861971946594,3064181181957632, 112806282518694969,4459192457431503104, 188376562263115020076,8469292812455408254464, 403767081039021522624615] |