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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 131 |
| 7 | 421 |
| 8 | 1385 |
| 9 | 4642 |
| 10 | 15795 |
| 11 | 54418 |
| 12 | 189454 |
| 13 | 665471 |
| 14 | 2355510 |
| 15 | 8393461 |
| 16 | 30084695 |
| 17 | 108394449 |
| 18 | 392356788 |
| 19 | 1426137550 |
| 20 | 5203211200 |
| 21 | 19048447855 |
| 22 | 69951072700 |
| 23 | 257609070810 |
| 24 | 951172531880 |
| 25 | 3520465229446 |
| 26 | 13058843476526 |
| 27 | 48540377627407 |
[1,1,2,5,14,42,131,421,1385,4642,15795,54418, 189454,665471,2355510,8393461,30084695,108394449, 392356788,1426137550,5203211200,19048447855, 69951072700,257609070810,951172531880, 3520465229446,13058843476526,48540377627407] |