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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 9 |
| 5 | 21 |
| 6 | 55 |
| 7 | 140 |
| 8 | 364 |
| 9 | 945 |
| 10 | 2465 |
| 11 | 6435 |
| 12 | 16821 |
| 13 | 43992 |
| 14 | 115102 |
| 15 | 301223 |
| 16 | 788425 |
| 17 | 2063817 |
| 18 | 5402651 |
| 19 | 14143524 |
| 20 | 37026936 |
| 21 | 96935685 |
| 22 | 253777537 |
| 23 | 664392743 |
| 24 | 1739393929 |
| 25 | 4553778096 |
| 26 | 11921922650 |
| 27 | 31211961195 |
| 28 | 81713914569 |
| 29 | 213929707485 |
| 30 | 560075086495 |
| 31 | 1466295355580 |
| 32 | 3838810662436 |
| 33 | 10050136117497 |
[1,2,3,9,21,55,140,364,945,2465,6435,16821,43992, 115102,301223,788425,2063817,5402651,14143524, 37026936,96935685,253777537,664392743,1739393929, 4553778096,11921922650,31211961195,81713914569, 213929707485,560075086495,1466295355580, 3838810662436,10050136117497] |