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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 22 |
| 4 | 273 |
| 5 | 4956 |
| 6 | 122215 |
| 7 | 3909228 |
| 8 | 156878337 |
| 9 | 7694191648 |
| 10 | 451507161771 |
| 11 | 31157580173160 |
| 12 | 2493155105671153 |
| 13 | 228656777880920832 |
| 14 | 23802477358410219183 |
| 15 | 2788676280294791340496 |
| 16 | 364998736798930722881025 |
| 17 | 53020798447231578364796928 |
[1,1,3,22,273,4956,122215,3909228,156878337, 7694191648,451507161771,31157580173160, 2493155105671153,228656777880920832, 23802477358410219183,2788676280294791340496, 364998736798930722881025, 53020798447231578364796928] |