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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 30 |
| 6 | 108 |
| 7 | 454 |
| 8 | 2186 |
| 9 | 11840 |
| 10 | 71254 |
| 11 | 471620 |
| 12 | 3405444 |
| 13 | 26638846 |
| 14 | 224412432 |
| 15 | 2025537526 |
| 16 | 19501264282 |
| 17 | 199486609542 |
| 18 | 2160670133172 |
| 19 | 24702689130878 |
| 20 | 297287351106034 |
| 21 | 3756625585698012 |
| 22 | 49730495350888890 |
| 23 | 688260442829860292 |
| 24 | 9939538985274953060 |
[1,1,2,4,10,30,108,454,2186,11840,71254,471620, 3405444,26638846,224412432,2025537526,19501264282, 199486609542,2160670133172,24702689130878, 297287351106034,3756625585698012, 49730495350888890,688260442829860292, 9939538985274953060] |