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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 12 |
| 5 | 41 |
| 6 | 133 |
| 7 | 485 |
| 8 | 1752 |
| 9 | 6677 |
| 10 | 25809 |
| 11 | 102130 |
| 12 | 409532 |
| 13 | 1665128 |
| 14 | 6837348 |
| 15 | 28333334 |
| 16 | 118288386 |
| 17 | 497120101 |
| 18 | 2101181482 |
| 19 | 8926401690 |
| 20 | 38093403136 |
| 21 | 163224292328 |
| 22 | 701951448268 |
| 23 | 3028792691947 |
| 24 | 13108224143298 |
| 25 | 56887750453404 |
| 26 | 247512117880754 |
| 27 | 1079421026637431 |
[1,1,4,12,41,133,485,1752,6677,25809,102130, 409532,1665128,6837348,28333334,118288386, 497120101,2101181482,8926401690,38093403136, 163224292328,701951448268,3028792691947, 13108224143298,56887750453404,247512117880754, 1079421026637431] |