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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 14 |
| 3 | 80 |
| 4 | 534 |
| 5 | 4102 |
| 6 | 35916 |
| 7 | 354888 |
| 8 | 3915750 |
| 9 | 47754938 |
| 10 | 637840356 |
| 11 | 9256590928 |
| 12 | 144977618044 |
| 13 | 2436460447020 |
| 14 | 43719637179224 |
| 15 | 834042701945520 |
| 16 | 16852447379512710 |
| 17 | 359468276129261730 |
| 18 | 8070500634880125300 |
| 19 | 190211302604157871680 |
| 20 | 4695001374741310892820 |
[1,3,14,80,534,4102,35916,354888,3915750,47754938, 637840356,9256590928,144977618044,2436460447020, 43719637179224,834042701945520,16852447379512710, 359468276129261730,8070500634880125300, 190211302604157871680,4695001374741310892820] |