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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 21 |
| 6 | 54 |
| 7 | 141 |
| 8 | 407 |
| 9 | 1231 |
| 10 | 3691 |
| 11 | 10990 |
| 12 | 33144 |
| 13 | 101674 |
| 14 | 314679 |
| 15 | 977289 |
| 16 | 3047527 |
| 17 | 9557503 |
| 18 | 30133759 |
| 19 | 95390622 |
| 20 | 302960929 |
| 21 | 965282651 |
| 22 | 3085146472 |
| 23 | 9888455045 |
| 24 | 31774215928 |
| 25 | 102334358736 |
| 26 | 330298415136 |
| 27 | 1068242904256 |
| 28 | 3461372341327 |
| 29 | 11235251353747 |
| 30 | 36527859658661 |
[1,1,1,2,7,21,54,141,407,1231,3691,10990,33144, 101674,314679,977289,3047527,9557503,30133759, 95390622,302960929,965282651,3085146472, 9888455045,31774215928,102334358736,330298415136, 1068242904256,3461372341327,11235251353747, 36527859658661] |