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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 18 |
| 5 | 44 |
| 6 | 107 |
| 7 | 257 |
| 8 | 621 |
| 9 | 1500 |
| 10 | 3620 |
| 11 | 8740 |
| 12 | 21101 |
| 13 | 50941 |
| 14 | 122983 |
| 15 | 296908 |
| 16 | 716798 |
| 17 | 1730504 |
| 18 | 4177807 |
| 19 | 10086117 |
| 20 | 24350041 |
| 21 | 58786200 |
| 22 | 141922440 |
| 23 | 342631080 |
| 24 | 827184601 |
| 25 | 1997000281 |
| 26 | 4821185163 |
| 27 | 11639370608 |
| 28 | 28099926378 |
| 29 | 67839223364 |
| 30 | 163778373107 |
[1,1,3,8,18,44,107,257,621,1500,3620,8740,21101, 50941,122983,296908,716798,1730504,4177807, 10086117,24350041,58786200,141922440,342631080, 827184601,1997000281,4821185163,11639370608, 28099926378,67839223364,163778373107] |