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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 101 |
| 6 | 490 |
| 7 | 2597 |
| 8 | 14926 |
| 9 | 92335 |
| 10 | 610503 |
| 11 | 4288517 |
| 12 | 31848677 |
| 13 | 249044068 |
| 14 | 2043448968 |
| 15 | 17540957166 |
| 16 | 157108128963 |
| 17 | 1464813176354 |
| 18 | 14187155168782 |
| 19 | 142469605397465 |
| 20 | 1480903718595721 |
| 21 | 15908940627242898 |
| 22 | 176382950500197589 |
| 23 | 2015650339677868116 |
[0,1,2,6,23,101,490,2597,14926,92335,610503, 4288517,31848677,249044068,2043448968,17540957166, 157108128963,1464813176354,14187155168782, 142469605397465,1480903718595721, 15908940627242898,176382950500197589, 2015650339677868116] |