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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 11 |
| 3 | 70 |
| 4 | 505 |
| 5 | 3910 |
| 6 | 31772 |
| 7 | 267280 |
| 8 | 2307982 |
| 9 | 20339946 |
| 10 | 182207333 |
| 11 | 1654250474 |
| 12 | 15187764411 |
| 13 | 140767293560 |
| 14 | 1315349040350 |
| 15 | 12377806027892 |
| 16 | 117200381305538 |
| 17 | 1115791797318548 |
| 18 | 10674418686087377 |
| 19 | 102563189093302366 |
| 20 | 989321056200478417 |
[1,2,11,70,505,3910,31772,267280,2307982,20339946, 182207333,1654250474,15187764411,140767293560, 1315349040350,12377806027892,117200381305538, 1115791797318548,10674418686087377, 102563189093302366,989321056200478417] |