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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 17 |
| 4 | 60 |
| 5 | 226 |
| 6 | 878 |
| 7 | 3492 |
| 8 | 14250 |
| 9 | 58967 |
| 10 | 247213 |
| 11 | 1050601 |
| 12 | 4505573 |
| 13 | 19469075 |
| 14 | 84748283 |
| 15 | 371246371 |
| 16 | 1635403490 |
| 17 | 7239344680 |
| 18 | 32181864157 |
| 19 | 143633949423 |
| 20 | 643403070160 |
| 21 | 2891371864494 |
| 22 | 13031676339188 |
| 23 | 58894497082146 |
| 24 | 266832924329883 |
| 25 | 1211747799396353 |
| 26 | 5514556962414231 |
| 27 | 25145923688951851 |
[1,2,5,17,60,226,878,3492,14250,58967,247213, 1050601,4505573,19469075,84748283,371246371, 1635403490,7239344680,32181864157,143633949423, 643403070160,2891371864494,13031676339188, 58894497082146,266832924329883,1211747799396353, 5514556962414231,25145923688951851] |