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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 48 |
| 8 | 113 |
| 9 | 275 |
| 10 | 667 |
| 11 | 1627 |
| 12 | 3951 |
| 13 | 9597 |
| 14 | 23215 |
| 15 | 56063 |
| 16 | 134982 |
| 17 | 324340 |
| 18 | 777492 |
| 19 | 1860365 |
| 20 | 4442905 |
| 21 | 10593324 |
| 22 | 25217480 |
| 23 | 59944219 |
| 24 | 142295011 |
| 25 | 337344737 |
| 26 | 798769090 |
| 27 | 1889131816 |
| 28 | 4462891151 |
| 29 | 10531873564 |
| 30 | 24828302752 |
[1,1,1,2,4,9,20,48,113,275,667,1627,3951,9597, 23215,56063,134982,324340,777492,1860365,4442905, 10593324,25217480,59944219,142295011,337344737, 798769090,1889131816,4462891151,10531873564, 24828302752] |