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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 27 |
| 4 | 255 |
| 5 | 1 |
| 6 | 3094 |
| 7 | 31 |
| 8 | 45865 |
| 9 | 791 |
| 10 | 803424 |
| 11 | 20119 |
| 12 | 16239720 |
| 13 | 528991 |
| 14 | 8505 |
| 15 | 372076163 |
| 16 | 14689441 |
| 17 | 654885 |
| 18 | 9529560676 |
| 19 | 435580164 |
| 20 | 34859160 |
| 21 | 269819334245 |
| 22 | 13846282341 |
| 23 | 1646054025 |
| 24 | 8369112382488 |
| 25 | 471890017358 |
| 26 | 73811825010 |
| 27 | 1286223400 |
[1,1,4,27,255,1,3094,31,45865,791,803424,20119, 16239720,528991,8505,372076163,14689441,654885, 9529560676,435580164,34859160,269819334245, 13846282341,1646054025,8369112382488,471890017358, 73811825010,1286223400] |