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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 2 |
| 8 | 5 |
| 9 | 10 |
| 10 | 17 |
| 11 | 30 |
| 12 | 77 |
| 13 | 254 |
| 14 | 873 |
| 15 | 2865 |
| 16 | 9282 |
| 17 | 36476 |
| 18 | 176379 |
| 19 | 950600 |
| 20 | 5334620 |
| 21 | 30998066 |
| 22 | 200015663 |
| 23 | 1516056134 |
| 24 | 12927161092 |
| 25 | 120013319909 |
| 26 | 1186872290095 |
| 27 | 12868902178120 |
| 28 | 156796551881590 |
[1,1,1,1,1,1,2,5,10,17,30,77,254,873,2865,9282, 36476,176379,950600,5334620,30998066,200015663, 1516056134,12927161092,120013319909,1186872290095, 12868902178120,156796551881590] |