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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 13 |
| 5 | 31 |
| 6 | 94 |
| 7 | 288 |
| 8 | 926 |
| 9 | 2877 |
| 10 | 9891 |
| 11 | 33305 |
| 12 | 114060 |
| 13 | 398440 |
| 14 | 1416214 |
| 15 | 5011681 |
| 16 | 18123463 |
| 17 | 65923411 |
| 18 | 241065146 |
| 19 | 890520980 |
| 20 | 3316802411 |
| 21 | 12381311497 |
| 22 | 46575028978 |
| 23 | 176069708511 |
| 24 | 667781099894 |
| 25 | 2545534958577 |
| 26 | 9747336415753 |
| 27 | 37437157140905 |
| 28 | 144427380938415 |
| 29 | 559178373691931 |
| 30 | 2170662589743925 |
[1,1,2,4,13,31,94,288,926,2877,9891,33305,114060, 398440,1416214,5011681,18123463,65923411, 241065146,890520980,3316802411,12381311497, 46575028978,176069708511,667781099894, 2545534958577,9747336415753,37437157140905, 144427380938415,559178373691931,2170662589743925] |