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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 15 |
| 4 | 254 |
| 5 | 5130 |
| 6 | 122119 |
| 7 | 3365089 |
| 8 | 105599276 |
| 9 | 3722336388 |
| 10 | 145717348221 |
| 11 | 6275071262691 |
| 12 | 294890141047050 |
| 13 | 15020233818893550 |
| 14 | 824373714907080675 |
| 15 | 48505985450168267925 |
| 16 | 3046201904592803410200 |
| 17 | 203381159927362120499400 |
| 18 | 14385952383695375700375225 |
[0,0,1,15,254,5130,122119,3365089,105599276, 3722336388,145717348221,6275071262691, 294890141047050,15020233818893550, 824373714907080675,48505985450168267925, 3046201904592803410200,203381159927362120499400, 14385952383695375700375225] |