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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 73 |
| 6 | 238 |
| 7 | 721 |
| 8 | 2044 |
| 9 | 5492 |
| 10 | 14178 |
| 11 | 35610 |
| 12 | 87938 |
| 13 | 215295 |
| 14 | 525787 |
| 15 | 1286294 |
| 16 | 3160692 |
| 17 | 7812235 |
| 18 | 19435271 |
| 19 | 48669058 |
| 20 | 122640467 |
| 21 | 310825886 |
| 22 | 791852703 |
| 23 | 2026485203 |
| 24 | 5206520173 |
| 25 | 13421671869 |
| 26 | 34697109772 |
| 27 | 89909564367 |
| 28 | 233436502611 |
| 29 | 607059621989 |
| 30 | 1580760867164 |
| 31 | 4120657531699 |
[1,1,2,6,21,73,238,721,2044,5492,14178,35610, 87938,215295,525787,1286294,3160692,7812235, 19435271,48669058,122640467,310825886,791852703, 2026485203,5206520173,13421671869,34697109772, 89909564367,233436502611,607059621989, 1580760867164,4120657531699] |