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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 93 |
| 5 | 649 |
| 6 | 4924 |
| 7 | 40221 |
| 8 | 344817 |
| 9 | 3058115 |
| 10 | 27798895 |
| 11 | 257009431 |
| 12 | 2404734586 |
| 13 | 22679499148 |
| 14 | 214947515333 |
| 15 | 2042353663088 |
| 16 | 19417906390395 |
| 17 | 184458621283607 |
| 18 | 1748712359825873 |
| 19 | 16530801697256737 |
| 20 | 155736745914813741 |
| 21 | 1461877902947680987 |
| 22 | 13674142992787617967 |
[1,1,3,16,93,649,4924,40221,344817,3058115, 27798895,257009431,2404734586,22679499148, 214947515333,2042353663088,19417906390395, 184458621283607,1748712359825873, 16530801697256737,155736745914813741, 1461877902947680987,13674142992787617967] |