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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 19 |
| 5 | 99 |
| 6 | 624 |
| 7 | 3684 |
| 8 | 23379 |
| 9 | 144877 |
| 10 | 927084 |
| 11 | 5882776 |
| 12 | 37925111 |
| 13 | 243908212 |
| 14 | 1582102118 |
| 15 | 10261788552 |
| 16 | 66893579077 |
| 17 | 436419943039 |
| 18 | 2856304168480 |
| 19 | 18714325924703 |
| 20 | 122881818022921 |
| 21 | 807744978199879 |
| 22 | 5318012331907328 |
[1,1,3,19,99,624,3684,23379,144877,927084,5882776, 37925111,243908212,1582102118,10261788552, 66893579077,436419943039,2856304168480, 18714325924703,122881818022921,807744978199879, 5318012331907328] |