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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
| 7 | 6 |
| 8 | 30 |
| 9 | 69 |
| 10 | 230 |
| 11 | 662 |
| 12 | 2244 |
| 13 | 6197 |
| 14 | 20782 |
| 15 | 57963 |
| 16 | 185236 |
| 17 | 534294 |
| 18 | 1636436 |
| 19 | 4788888 |
| 20 | 14148505 |
| 21 | 41505698 |
| 22 | 119551191 |
| 23 | 347802192 |
| 24 | 984873101 |
| 25 | 2823972122 |
| 26 | 7899999963 |
| 27 | 22281193586 |
| 28 | 61710573450 |
| 29 | 171287868395 |
| 30 | 469925476292 |
[1,1,1,1,2,2,6,30,69,230,662,2244,6197,20782, 57963,185236,534294,1636436,4788888,14148505, 41505698,119551191,347802192,984873101,2823972122, 7899999963,22281193586,61710573450,171287868395, 469925476292] |