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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 74 |
| 5 | 531 |
| 6 | 4563 |
| 7 | 45753 |
| 8 | 524345 |
| 9 | 6760039 |
| 10 | 96837333 |
| 11 | 1525909903 |
| 12 | 26230304235 |
| 13 | 488472319271 |
| 14 | 9796281435125 |
| 15 | 210496933103743 |
| 16 | 4824574494068495 |
| 17 | 117490079786298641 |
| 18 | 3029472152485535343 |
| 19 | 82454398253005541089 |
| 20 | 2362311059301928969755 |
| 21 | 71063998308414194250901 |
[1,1,3,13,74,531,4563,45753,524345,6760039, 96837333,1525909903,26230304235,488472319271, 9796281435125,210496933103743,4824574494068495, 117490079786298641,3029472152485535343, 82454398253005541089,2362311059301928969755, 71063998308414194250901] |