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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 37 |
| 5 | 128 |
| 6 | 439 |
| 7 | 1508 |
| 8 | 5179 |
| 9 | 17779 |
| 10 | 61033 |
| 11 | 209522 |
| 12 | 719266 |
| 13 | 2469165 |
| 14 | 8476377 |
| 15 | 29098491 |
| 16 | 99891986 |
| 17 | 342918422 |
| 18 | 1177201983 |
| 19 | 4041207525 |
| 20 | 13873029857 |
| 21 | 47624616207 |
| 22 | 163490174266 |
| 23 | 561244146614 |
[0,1,3,10,37,128,439,1508,5179,17779,61033,209522, 719266,2469165,8476377,29098491,99891986, 342918422,1177201983,4041207525,13873029857, 47624616207,163490174266,561244146614] |