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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 31 |
| 4 | 219 |
| 5 | 1672 |
| 6 | 13439 |
| 7 | 112043 |
| 8 | 960017 |
| 9 | 8402085 |
| 10 | 74791408 |
| 11 | 675033956 |
| 12 | 6163120105 |
| 13 | 56820187321 |
| 14 | 528231686315 |
| 15 | 4946304326883 |
| 16 | 46609889424547 |
| 17 | 441664236745594 |
| 18 | 4205848369345681 |
| 19 | 40228631544942031 |
| 20 | 386317524696654392 |
| 21 | 3723196299965400616 |
[1,1,5,31,219,1672,13439,112043,960017,8402085, 74791408,675033956,6163120105,56820187321, 528231686315,4946304326883,46609889424547, 441664236745594,4205848369345681, 40228631544942031,386317524696654392, 3723196299965400616] |