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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 21 |
| 3 | 185 |
| 4 | 18655 |
| 5 | 307503 |
| 6 | 12548151 |
| 7 | 305496477 |
| 8 | 138343008375 |
| 9 | 4464248592375 |
| 10 | 323592065474535 |
| 11 | 13015087974100485 |
| 12 | 2301190559547593805 |
| 13 | 110887163426713235625 |
| 14 | 11570760017278599886875 |
| 15 | 649837647729572203369125 |
| 16 | 1250848387902442801195686375 |
| 17 | 80233244659365977333374518375 |
[0,1,21,185,18655,307503,12548151,305496477, 138343008375,4464248592375,323592065474535, 13015087974100485,2301190559547593805, 110887163426713235625,11570760017278599886875, 649837647729572203369125, 1250848387902442801195686375, 80233244659365977333374518375] |