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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 15 |
| 6 | 37 |
| 7 | 100 |
| 8 | 283 |
| 9 | 851 |
| 10 | 2693 |
| 11 | 8934 |
| 12 | 30951 |
| 13 | 111597 |
| 14 | 417560 |
| 15 | 1617203 |
| 16 | 6468815 |
| 17 | 26671611 |
| 18 | 113158063 |
| 19 | 493244564 |
| 20 | 2205856753 |
| 21 | 10108505544 |
| 22 | 47413093714 |
| 23 | 227385209452 |
| 24 | 1113955476429 |
| 25 | 5569777382145 |
| 26 | 28400403557928 |
| 27 | 147572825753377 |
| 28 | 780881994429009 |
[1,1,2,3,6,15,37,100,283,851,2693,8934,30951, 111597,417560,1617203,6468815,26671611,113158063, 493244564,2205856753,10108505544,47413093714, 227385209452,1113955476429,5569777382145, 28400403557928,147572825753377,780881994429009] |