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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 41 |
| 6 | 162 |
| 7 | 714 |
| 8 | 3397 |
| 9 | 17251 |
| 10 | 92048 |
| 11 | 509444 |
| 12 | 2893683 |
| 13 | 16734381 |
| 14 | 97965934 |
| 15 | 578241694 |
| 16 | 3431848769 |
| 17 | 20442513431 |
| 18 | 122066210220 |
| 19 | 730058053464 |
| 20 | 4371040179055 |
| 21 | 26189154314401 |
| 22 | 156987015743306 |
| 23 | 941331763528754 |
[1,1,4,11,41,162,714,3397,17251,92048,509444, 2893683,16734381,97965934,578241694,3431848769, 20442513431,122066210220,730058053464, 4371040179055,26189154314401,156987015743306, 941331763528754] |