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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 37 |
| 6 | 87 |
| 7 | 241 |
| 8 | 793 |
| 9 | 2513 |
| 10 | 7437 |
| 11 | 22287 |
| 12 | 70051 |
| 13 | 222883 |
| 14 | 700213 |
| 15 | 2195139 |
| 16 | 6959869 |
| 17 | 22252933 |
| 18 | 71201129 |
| 19 | 227826699 |
| 20 | 731309001 |
| 21 | 2356460041 |
| 22 | 7609531843 |
| 23 | 24603325189 |
| 24 | 79677148959 |
| 25 | 258535824775 |
| 26 | 840291483835 |
| 27 | 2734637778217 |
| 28 | 8910389207081 |
| 29 | 29069537051081 |
[1,1,1,3,13,37,87,241,793,2513,7437,22287,70051, 222883,700213,2195139,6959869,22252933,71201129, 227826699,731309001,2356460041,7609531843, 24603325189,79677148959,258535824775,840291483835, 2734637778217,8910389207081,29069537051081] |