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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 31 |
| 2 | 495 |
| 3 | 5424 |
| 4 | 45848 |
| 5 | 318649 |
| 6 | 1895464 |
| 7 | 9919009 |
| 8 | 46584724 |
| 9 | 199347764 |
| 10 | 786519756 |
| 11 | 2888400232 |
| 12 | 9950014727 |
| 13 | 32360135292 |
| 14 | 99903188872 |
| 15 | 294134516323 |
| 16 | 829176461458 |
| 17 | 2245909515022 |
| 18 | 5862798149046 |
| 19 | 14789460753680 |
| 20 | 36138546144580 |
[1,31,495,5424,45848,318649,1895464,9919009, 46584724,199347764,786519756,2888400232, 9950014727,32360135292,99903188872,294134516323, 829176461458,2245909515022,5862798149046, 14789460753680,36138546144580] |