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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 42 |
| 4 | 224 |
| 5 | 1281 |
| 6 | 7630 |
| 7 | 46816 |
| 8 | 294008 |
| 9 | 1880588 |
| 10 | 12209474 |
| 11 | 80251889 |
| 12 | 532988530 |
| 13 | 3571260662 |
| 14 | 24112334292 |
| 15 | 163887278097 |
| 16 | 1120445503036 |
| 17 | 7699924478714 |
| 18 | 53160597794588 |
| 19 | 368549236730128 |
| 20 | 2564649436452878 |
| 21 | 17907555498455680 |
| 22 | 125426544531794332 |
[1,2,8,42,224,1281,7630,46816,294008,1880588, 12209474,80251889,532988530,3571260662, 24112334292,163887278097,1120445503036, 7699924478714,53160597794588,368549236730128, 2564649436452878,17907555498455680, 125426544531794332] |