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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 36 |
| 4 | 251 |
| 5 | 1881 |
| 6 | 14817 |
| 7 | 120950 |
| 8 | 1014042 |
| 9 | 8680377 |
| 10 | 75552553 |
| 11 | 666614637 |
| 12 | 5948817600 |
| 13 | 53599239101 |
| 14 | 486926148000 |
| 15 | 4455202562652 |
| 16 | 41018936164660 |
| 17 | 379747493741643 |
| 18 | 3532914858433284 |
| 19 | 33012260400580342 |
| 20 | 309692626084981245 |
| 21 | 2915659701275923491 |
[1,1,6,36,251,1881,14817,120950,1014042,8680377, 75552553,666614637,5948817600,53599239101, 486926148000,4455202562652,41018936164660, 379747493741643,3532914858433284, 33012260400580342,309692626084981245, 2915659701275923491] |