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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 38 |
| 4 | 201 |
| 5 | 1134 |
| 6 | 6688 |
| 7 | 40734 |
| 8 | 254237 |
| 9 | 1617572 |
| 10 | 10452416 |
| 11 | 68408626 |
| 12 | 452530659 |
| 13 | 3020870352 |
| 14 | 20324167488 |
| 15 | 137672551630 |
| 16 | 938154745773 |
| 17 | 6426806842566 |
| 18 | 44234352581896 |
| 19 | 305743015718028 |
| 20 | 2121318029754770 |
| 21 | 14769052147618740 |
| 22 | 103148538125870880 |
[1,2,8,38,201,1134,6688,40734,254237,1617572, 10452416,68408626,452530659,3020870352, 20324167488,137672551630,938154745773, 6426806842566,44234352581896,305743015718028, 2121318029754770,14769052147618740, 103148538125870880] |