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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 4 |
| 6 | 16 |
| 7 | 175 |
| 8 | 5274 |
| 9 | 434017 |
| 10 | 90658149 |
| 11 | 48825116761 |
| 12 | 68579602126387 |
| 13 | 254236892409251687 |
| 14 | 2512196983110257299898 |
| 15 | 66738846701458593981832314 |
| 16 | 4802164152196181961357340585741 |
| 17 | 942009012794429918939576183310877477 |
| 18 | 506665422212653541096106256584713063500057 |
[1,1,0,1,1,4,16,175,5274,434017,90658149, 48825116761,68579602126387,254236892409251687, 2512196983110257299898,66738846701458593981832314, 4802164152196181961357340585741, 942009012794429918939576183310877477, 506665422212653541096106256584713063500057] |