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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 17 |
| 5 | 78 |
| 6 | 199 |
| 7 | 638 |
| 8 | 1865 |
| 9 | 5332 |
| 10 | 17250 |
| 11 | 50877 |
| 12 | 156787 |
| 13 | 475348 |
| 14 | 1423432 |
| 15 | 4367178 |
| 16 | 13182353 |
| 17 | 40122074 |
| 18 | 121916294 |
| 19 | 369052634 |
| 20 | 1122475534 |
| 21 | 3403574961 |
| 22 | 10335095973 |
| 23 | 31385295907 |
| 24 | 95218937465 |
| 25 | 289154182737 |
| 26 | 877572289140 |
| 27 | 2663965244527 |
| 28 | 8087517963748 |
[1,1,3,7,17,78,199,638,1865,5332,17250,50877, 156787,475348,1423432,4367178,13182353,40122074, 121916294,369052634,1122475534,3403574961, 10335095973,31385295907,95218937465,289154182737, 877572289140,2663965244527,8087517963748] |