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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 154 |
| 7 | 675 |
| 8 | 3534 |
| 9 | 18985 |
| 10 | 108070 |
| 11 | 632109 |
| 12 | 3807254 |
| 13 | 23411290 |
| 14 | 146734695 |
| 15 | 934382820 |
| 16 | 6034524474 |
| 17 | 39457153432 |
| 18 | 260855420489 |
| 19 | 1741645762265 |
| 20 | 11732357675908 |
| 21 | 79673115468562 |
| 22 | 545036528857605 |
| 23 | 3753642607424647 |
| 24 | 26010818244754788 |
| 25 | 181266500331748878 |
[1,1,2,4,12,34,154,675,3534,18985,108070,632109, 3807254,23411290,146734695,934382820,6034524474, 39457153432,260855420489,1741645762265, 11732357675908,79673115468562,545036528857605, 3753642607424647,26010818244754788, 181266500331748878] |