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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 64 |
| 3 | 1778 |
| 4 | 73848 |
| 5 | 4188592 |
| 6 | 306690520 |
| 7 | 27893327856 |
| 8 | 3063657097664 |
| 9 | 397720778283584 |
| 10 | 59997757426314624 |
| 11 | 10373545999796847232 |
| 12 | 2032368096229682220160 |
| 13 | 446879795164524710777856 |
[1,4,64,1778,73848,4188592,306690520,27893327856, 3063657097664,397720778283584,59997757426314624, 10373545999796847232,2032368096229682220160, 446879795164524710777856] |