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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 68 |
| 3 | 424 |
| 4 | 2576 |
| 5 | 15520 |
| 6 | 93248 |
| 7 | 559744 |
| 8 | 3358976 |
| 9 | 20154880 |
| 10 | 120931328 |
| 11 | 725592064 |
| 12 | 4353560576 |
| 13 | 26121379840 |
| 14 | 156728311808 |
| 15 | 940369936384 |
| 16 | 5642219749376 |
| 17 | 33853318758400 |
| 18 | 203119913074688 |
| 19 | 1218719479496704 |
| 20 | 7312316879077376 |
| 21 | 43873901278658560 |
| 22 | 263243407680339968 |
[1,10,68,424,2576,15520,93248,559744,3358976, 20154880,120931328,725592064,4353560576, 26121379840,156728311808,940369936384, 5642219749376,33853318758400,203119913074688, 1218719479496704,7312316879077376, 43873901278658560,263243407680339968] |