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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 12 |
| 5 | 28 |
| 6 | 94 |
| 7 | 298 |
| 8 | 1044 |
| 9 | 3658 |
| 10 | 13164 |
| 11 | 47710 |
| 12 | 174948 |
| 13 | 645436 |
| 14 | 2397342 |
| 15 | 8948416 |
| 16 | 33556500 |
| 17 | 126324496 |
| 18 | 477225962 |
| 19 | 1808414182 |
| 20 | 6871973952 |
| 21 | 26178873448 |
| 22 | 99955697946 |
| 23 | 382438918234 |
| 24 | 1466015854100 |
| 25 | 5629499869780 |
[1,1,3,4,12,28,94,298,1044,3658,13164,47710, 174948,645436,2397342,8948416,33556500,126324496, 477225962,1808414182,6871973952,26178873448, 99955697946,382438918234,1466015854100, 5629499869780] |