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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 399 |
| 3 | 8127 |
| 4 | 184436 |
| 5 | 4695719 |
| 6 | 133730310 |
| 7 | 4234560596 |
| 8 | 148077895854 |
| 9 | 5680484146379 |
| 10 | 237574859841676 |
| 11 | 10771591113205720 |
| 12 | 526750324271281348 |
| 13 | 27655229128194306702 |
| 14 | 1552379671658643163707 |
| 15 | 92820542631741826797326 |
[1,21,399,8127,184436,4695719,133730310, 4234560596,148077895854,5680484146379, 237574859841676,10771591113205720, 526750324271281348,27655229128194306702, 1552379671658643163707,92820542631741826797326] |