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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 221 |
| 5 | 3117 |
| 6 | 54597 |
| 7 | 1136127 |
| 8 | 27293715 |
| 9 | 742143113 |
| 10 | 22512196673 |
| 11 | 753402861159 |
| 12 | 27571631761077 |
| 13 | 1095346704175755 |
| 14 | 46948527167219957 |
| 15 | 2159638211148320085 |
| 16 | 106129271000784614099 |
| 17 | 5549226963359699829711 |
| 18 | 307623817602110038648839 |
| 19 | 18022345501064909362595723 |
| 20 | 1112657716434830018636702797 |
[1,1,3,21,221,3117,54597,1136127,27293715, 742143113,22512196673,753402861159,27571631761077, 1095346704175755,46948527167219957, 2159638211148320085,106129271000784614099, 5549226963359699829711,307623817602110038648839, 18022345501064909362595723, 1112657716434830018636702797] |