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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 25 |
| 4 | 121 |
| 5 | 861 |
| 6 | 10051 |
| 7 | 88453 |
| 8 | 972945 |
| 9 | 16663321 |
| 10 | 205667011 |
| 11 | 3069838641 |
| 12 | 61038456073 |
| 13 | 997387656565 |
| 14 | 18623707785411 |
| 15 | 426663334715101 |
| 16 | 8606752819074721 |
| 17 | 192052302116929713 |
| 18 | 5139946157328092035 |
| 19 | 122142504609497184841 |
| 20 | 3172736666738570349081 |
| 21 | 94751480557190553846541 |
[1,1,3,25,121,861,10051,88453,972945,16663321, 205667011,3069838641,61038456073,997387656565, 18623707785411,426663334715101,8606752819074721, 192052302116929713,5139946157328092035, 122142504609497184841,3172736666738570349081, 94751480557190553846541] |