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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 37 |
| 4 | 150 |
| 5 | 653 |
| 6 | 2990 |
| 7 | 14157 |
| 8 | 68470 |
| 9 | 335533 |
| 10 | 1657470 |
| 11 | 8227277 |
| 12 | 40957190 |
| 13 | 204250413 |
| 14 | 1019649550 |
| 15 | 5093448397 |
| 16 | 25452860310 |
| 17 | 127221189293 |
| 18 | 635976675230 |
| 19 | 3179495693517 |
| 20 | 15896315681830 |
| 21 | 79478090576173 |
| 22 | 397379990430510 |
[1,3,10,37,150,653,2990,14157,68470,335533, 1657470,8227277,40957190,204250413,1019649550, 5093448397,25452860310,127221189293,635976675230, 3179495693517,15896315681830,79478090576173, 397379990430510] |